Turbo breakdown solutions

How to identify a fault in your turbo

This problem analysis will make it easier for you to determine the cause of a turbocharger malfunction. Bear in mind that, in the event of a turbocharger malfunction, the turbocharger should be considered as a component of the engine block. The damage may be more extensive than you first thought.

Follow the steps in this problem analysis one by one: you're likely to find the answer to your question.

Select the description most appropriate to your situation:

Checking the turbocharger

Dismantling the pipe connecting the air filter to the turbocharger allows you to feel the rotor clearance. If the radial clearance is such that the wheels are rubbing against the housing, the turbocharger has worn excessively. We recommend replacing the turbocharger immediately. If the play is not excessive, go on to the next step.

Symptoms of your turbocharger failure:

Irregular turbocharger noise

Blocked air intake between air filter and turbocharger

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes oil to leak from the turbocharger. This oil leakage reaches the compressor wheel, causing a resonance effect due to the high speed of the turbocharger.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Air supply to turbocharger blocked

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes oil to leak from the turbocharger. This oil leakage reaches the compressor wheel, causing a resonance effect due to the high speed of the turbocharger.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Contaminated turbocharger compressor rating

The presence of impurities on the compressor side prevents the turbocharger from drawing in air freely. This creates a vacuum, which causes oil to leak from the turbocharger. This oil leakage reaches the compressor wheel, causing a resonance effect due to the high speed of the turbocharger.

Solution


We recommend that you thoroughly clean the compressor side using a non-corrosive product and a soft brush. Then determine the cause of the contamination to ensure that it does not recur in the short term.
Excessive turbocharger noise

Blocked air intake between air filter and turbocharger

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes oil to leak from the turbocharger. This oil leakage reaches the compressor wheel, causing a resonance effect due to the high speed of the turbocharger.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Air supply to turbocharger blocked

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes oil to leak from the turbocharger. This oil leakage reaches the compressor wheel, causing a resonance effect due to the high speed of the turbocharger.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Contaminated turbocharger compressor rating

The presence of impurities on the compressor side prevents the turbocharger from drawing in air freely. This creates a vacuum, which causes oil to leak from the turbocharger. This oil leakage reaches the compressor wheel, causing a resonance effect due to the high speed of the turbocharger.

Solution


We recommend that you thoroughly clean the compressor side using a non-corrosive product and a soft brush. Then determine the cause of the contamination to ensure that it does not recur in the short term.

Air leak in the duct between the air filter and the turbocharger

An air leak can cause oil to leak from the turbocharger. This oil leak reaches the compressor wheel, causing a resonance effect due to the high speed of the turbocharger. The air flow escaping to the outside via the leak also emits a whistling sound.

Solution


Plug the leak by applying hose clips or replacing damaged areas.

Air leak between intake manifold and cylinder head

An air leak can cause oil to leak from the turbocharger. This oil leak reaches the compressor wheel, causing a resonance effect due to the high speed of the turbocharger. The air flow escaping to the outside via the leak also emits a whistling sound.

Solution


Replace damaged seals and check all fasteners thoroughly. Refer to the manufacturer's manual for further information.

Air leak between turbocharger and intake manifold

An air leak can cause oil to leak from the turbocharger. This oil leak reaches the compressor wheel, causing a resonance effect due to the high speed of the turbocharger. The air flow escaping to the outside via the leak also emits a whistling sound.

Solution


Make sure you repair the leak by applying hose clips or replacing the defective parts. This will immediately improve the pressure supplied by the turbocharger.

Exhaust gas leak between cylinder head and exhaust manifold

Exhaust gases escaping to the outside emit a whistling sound due to the speed of the gas flow.

Solution


Replace damaged seals and check all fasteners thoroughly. Refer to the manufacturer's manual for further information.

Exhaust gas leak between the exhaust manifold and the turbocharger

Exhaust gases escaping to the outside emit a whistling sound due to the speed of the gas flow.

Solution


Replace damaged seals and check all fasteners thoroughly. Refer to the manufacturer's manual for further information.

Exhaust gas leak between turbocharger and exhaust pipe

Exhaust gases escaping to the outside emit a whistling sound due to the speed of the gas flow.

Solution


Repair the leak or replace damaged parts.
Excessive oil consumption

Blocked air intake between air filter and turbocharger

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes oil to leak from the turbocharger. The oil does not return to the crankcase, resulting in excessive oil consumption.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Air supply to turbocharger blocked

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes oil to leak from the turbocharger. The oil does not return to the crankcase, resulting in excessive oil consumption.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Blocked oil pipe

When the turbocharger oil pipe is blocked, the oil does not escape from the turbocharger quickly enough. The oil therefore has to follow a different path, and presses the turbocharger seals outwards, on both the compressor and turbine sides. The oil therefore does not return to the crankcase, resulting in excessive oil consumption.

Solution


Clean or replace if necessary.

Turbocharger bearing housing blocked or carbonised

When the bearing housing is blocked or carbonised, the oil does not leave the turbocharger quickly enough. The oil therefore has to follow a different path, and presses the turbocharger seals outwards, on both the compressor and turbine sides. The oil therefore does not return to the crankcase, resulting in excessive oil consumption.

Solution


Change the oil and replace the oil filter. Have the turbocharger repaired or replaced.

Contaminated turbocharger compressor rating

The presence of impurities on the compressor side prevents the turbocharger from drawing in air freely. This creates a vacuum, which causes oil to leak from the turbocharger. The oil does not return to the crankcase, resulting in excessive oil consumption.

Solution


We recommend that you thoroughly clean the compressor side using a non-corrosive product and a soft brush. Then determine the cause of the contamination to ensure that it does not recur in the short term.

Air leak between intake manifold and cylinder head

An air leak can cause the turbocharger to leak oil. The oil does not return to the crankcase, resulting in excessive oil consumption.

Solution


Replace damaged seals and check all fasteners thoroughly. Refer to the manufacturer's manual for further information.

Air leak between turbocharger and intake manifold

An air leak can cause the turbocharger to leak oil. The oil does not return to the crankcase, resulting in excessive oil consumption.

Solution


Make sure you repair the leak by applying hose clips or replacing the defective parts. This will immediately improve the pressure supplied by the turbocharger.

Crankcase ventilation malfunction

If the crankcase air outlet is blocked, back pressure builds up in the oil drain pipe, preventing the oil from leaving the turbocharger quickly enough. The oil therefore has to follow a different path, and presses the turbocharger seals outwards, on both the compressor and turbine sides. The oil therefore does not return to the crankcase, resulting in excessive oil consumption.

Solution


Proceed with cleaning, and refer to the motor manufacturer's manual.

Used piston rings and/or cylinder liners

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.

Engine wear

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.
Intake manifold pressure too high

Pressure relief valve blocked

When the pressure relief valve or the unloading valve is blocked in the open position, the turbine is not sufficiently driven. As a result, there is insufficient pressure in the turbocharger, and engine power falls.

Solution


Test, adjust and replace atomisers if necessary
Intake manifold pressure too low

Faulty turbocharger/intake manifold pressure sensor

The pressure measured is insufficient if the turbocharger pressure sensor malfunctions. This means that the system will require additional turbocharger pressure, which the turbocharger cannot provide because it is impossible to increase the engine speed above that of high gears. The intake manifold underpressure is therefore insufficient.

Solution


Replace the turbocharger pressure sensor.

Mouth catalyst

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


We recommend that you clean and, if possible, replace the catalytic converter. Refer to the manufacturer's manual for further information.

Faulty air flow meter

The air flow meter no longer reacts normally when its sensors are contaminated. As a result, the amount of fuel injected is insufficient, and the under-pressure at the intake manifold becomes too low.

Solution


Clean or replace if necessary

EGR valve contaminated

When the EGR valve is contaminated, the amount of exhaust gas returned to the engine's combustion chamber is insufficient. The air/fuel ratio is therefore inappropriate, resulting in a loss of power in high gears. This is the only problem caused by this cause.

Solution


Clean or replace if necessary
Reduced engine power

Blocked air intake between air filter and turbocharger

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes the turbocharger pressure to drop. The engine is therefore no longer able to produce the desired power.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Blocked air intake between turbocharger and intake manifold

In this situation, the turbocharger reaches its normal speed, but the pressure it produces is not transmitted to the combustion chamber. The engine therefore receives insufficient pressure from the turbocharger, and cannot produce the desired power.

Solution


We advise you to check the air ducts carefully. Make sure that no dirt remains when you refit them. If there is serious damage to the pipes, replace them immediately. Failure to do so could damage the turbocharger.

Air supply to turbocharger blocked

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes the turbocharger pressure to drop. The engine is therefore no longer able to produce the desired power.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Camshaft and/or timing belt incorrectly adjusted

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.

Damaged turbocharger vacuum line

When the vacuum lines leading to the turbocharger are damaged, the turbocharger variable washer is not moved into the closed position. As a result, the turbocharger has insufficient pressure and the vehicle's power output is low.

Solution


Replace the vacuum pipe

Mouth catalyst

When the catalytic converter is blocked, the turbocharger cannot discharge its exhaust gases in time. This causes the turbine wheel to resist turning in the right direction. The turbocharger is therefore unable to reach the required speed, and delivers insufficient power.

Solution


We recommend that you clean and, if possible, replace the catalytic converter. Refer to the manufacturer's manual for further information.

Intake manifold

In this situation, the turbocharger reaches its normal speed, but the pressure it produces is not transmitted to the combustion chamber. The engine therefore receives insufficient pressure from the turbocharger, and cannot produce the desired power.

Solution


We advise you to check the intake manifold thoroughly. Clean the intake manifold thoroughly and make sure that no dirt remains when you refit it. If the manifold is seriously damaged, replace it immediately. Failure to do so could damage the turbocharger.

Exhaust manifold

When the exhaust manifold is blocked, the amount of exhaust gas collected by the turbocharger is insufficient. As the turbocharger is driven by the exhaust gases, it cannot reach the required speed and therefore transmits insufficient power.

Solution


We recommend that you clean and, if possible, replace the exhaust manifold. Refer to the manufacturer's manual for further information.

Contaminated turbocharger compressor rating

Contamination on the compressor side is likely to cause slight damage to the compressor wheel, resulting in reduced engine power. This may be due to dirt entering the turbocharger via the air filter, and may suggest that the compressor wheel is sandy. This damage causes insufficient air to be drawn into the turbine, resulting in low pressure. The engine is therefore no longer able to produce the desired power.

Solution


We recommend that you thoroughly clean the compressor side using a non-corrosive product and a soft brush. Then determine the cause of the contamination to ensure that it does not recur in the short term.

Air leak in the duct between the air filter and the turbocharger

An air leak means that the turbocharger loses pressure upstream of the combustion chamber, preventing the engine from transmitting its full power.

Solution


Plug the leak by applying hose clips or replacing damaged areas.

Air leak between intake manifold and cylinder head

An air leak means that the turbocharger loses pressure upstream of the combustion chamber, preventing the engine from transmitting its full power.

Solution


Replace damaged seals and check all fasteners thoroughly. Refer to the manufacturer's manual for further information.

Air leak between turbocharger and intake manifold

An air leak means that the turbocharger loses pressure upstream of the combustion chamber, preventing the engine from transmitting its full power.

Solution


Make sure you repair the leak by applying hose clips or replacing the defective parts. This will immediately improve the pressure supplied by the turbocharger.

Exhaust gas leak between cylinder head and exhaust manifold

If the exhaust gases leak before entering the turbocharger, this means that the amount of exhaust gas collected by the turbocharger is insufficient. As the turbocharger is driven by the exhaust gases, it cannot reach the required speed and therefore transmits insufficient power.

Solution


Replace damaged seals and check all fasteners thoroughly. Refer to the manufacturer's manual for further information.

Exhaust gas leak between the exhaust manifold and the turbocharger

If the exhaust gases leak before entering the turbocharger, this means that the amount of exhaust gas collected by the turbocharger is insufficient. As the turbocharger is driven by the exhaust gases, it cannot reach the required speed and therefore transmits insufficient power.

Solution


Replace damaged seals and check all fasteners thoroughly. Refer to the manufacturer's manual for further information.

Incorrectly adjusted fuel pumps or atomisers

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.

Intermediate cooler blocked or faulty

In this situation, the turbocharger reaches its normal speed, but the pressure it produces is not transmitted to the combustion chamber. The engine therefore receives insufficient pressure from the turbocharger, and cannot produce the desired power.

Solution


We advise you to check the intercooler thoroughly. Make sure that no dirt remains when you refit it. If the intercooler is seriously damaged, replace it immediately. Failure to do so could damage the turbocharger.

Used piston rings and/or cylinder liners

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.

Defective discharge valve

The build-up of soot or dirt can cause the turbocharger relief valve to block. The discharge valve remains in the open position, causing the exhaust gases to be discharged immediately when they should be driving the turbine. This logically leads to a loss of pressure in the turbocharger, and therefore a reduction in engine power.

Solution


We recommend that you carefully loosen the bar connecting the actuator to the pressure relief valve on the turbine housing. You can then check whether the relief valve complies with the standards. If not, try to bring it up to standard. If this is not possible, you should consider replacing the turbocharger.

Pressure relief valve blocked

When the pressure relief valve or the unloading valve is blocked in the open position, the turbine is not sufficiently driven. As a result, there is insufficient pressure in the turbocharger, and engine power falls.

Solution


Test, adjust and replace atomisers if necessary

Plugged exhaust pipe or silencer

When the exhaust pipe or silencer is blocked, the turbocharger cannot discharge its exhaust gases in time. This causes the turbine wheel to resist turning in the right direction. The turbocharger is therefore unable to reach the required speed, and delivers insufficient power.

Solution


We recommend that you clean and, if possible, replace the exhaust pipe and silencer. Refer to the manufacturer's manual for further information.

Engine wear

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.
Oil leak from compressor side

Blocked air intake between air filter and turbocharger

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes oil to leak from the turbocharger. The vacuum causes the oil to be drawn out of the turbocharger, towards the intake manifold.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Air supply to turbocharger blocked

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes oil to leak from the turbocharger. The vacuum causes the oil to be drawn out of the turbocharger, towards the intake manifold.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Blocked oil pipe

When the oil pipe is blocked, the oil does not escape from the turbocharger quickly enough. The oil therefore has to follow a different path, and presses the turbocharger seals outwards, on both the compressor and turbine sides. The oil reaches the combustion chamber via the compressor side of the turbocharger.

Solution


Clean or replace if necessary.

Turbocharger bearing housing blocked or carbonised

When the bearing housing is blocked or carbonised, the oil does not leave the turbocharger quickly enough. The oil therefore has to follow a different path, and presses the turbocharger seals outwards, on both the compressor and turbine sides. The oil reaches the combustion chamber via the compressor side of the turbocharger.

Solution


Change the oil and replace the oil filter. Have the turbocharger repaired or replaced.

Contaminated turbocharger compressor rating

The presence of impurities on the compressor side prevents the turbocharger from drawing in air freely. This creates a vacuum, which causes oil to leak from the turbocharger. The vacuum forces the oil out of the turbocharger and into the intake manifold.

Solution


We recommend that you thoroughly clean the compressor side using a non-corrosive product and a soft brush. Then determine the cause of the contamination to ensure that it does not recur in the short term.

Air leak in the duct between the air filter and the turbocharger

Air leakage can cause oil leakage from the turbocharger. This is because the seal in the turbocharger requires a certain amount of engine backpressure for optimum operation. For example, if you leave the engine running without connecting the turbocharger hose to the intake manifold, oil will leak from the turbocharger within a short time.

Solution


Plug the leak by applying hose clips or replacing damaged areas.

Air leak between intake manifold and cylinder head

Air leakage can cause oil leakage from the turbocharger. This is because the seal in the turbocharger requires a certain amount of engine backpressure for optimum operation. For example, if you leave the engine running without connecting the turbocharger hose to the intake manifold, oil will leak from the turbocharger within a short time.

Solution


Replace damaged seals and check all fasteners thoroughly. Refer to the manufacturer's manual for further information.

Air leak between turbocharger and intake manifold

Air leakage can cause oil leakage from the turbocharger. This is because the seal in the turbocharger requires a certain amount of engine backpressure for optimum operation. For example, if you leave the engine running without connecting the turbocharger hose to the intake manifold, oil will leak from the turbocharger within a short time.

Solution


Make sure you repair the leak by applying hose clips or replacing the defective parts. This will immediately improve the pressure supplied by the turbocharger.

Crankcase ventilation malfunction

If the crankcase air outlet is blocked, back pressure builds up in the oil drain pipe, preventing the oil from leaving the turbocharger quickly enough. The oil therefore has to follow a different path, and presses the turbocharger seals outwards, on both the compressor and turbine sides. The oil reaches the combustion chamber via the compressor side of the turbocharger.

Solution


Proceed with cleaning, and refer to the motor manufacturer's manual.

Used piston rings and/or cylinder liners

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.

Engine wear

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.
Oil leak on turbine side

Blocked oil pipe

When the oil pipe is blocked, the oil does not escape from the turbocharger quickly enough. The oil therefore has to follow a different path, and presses the seals outwards on the turbine side. This usually results in the formation of blue fumes, due to contact between the oil and the high-temperature exhaust area.

Solution


Clean or replace if necessary.

Turbocharger bearing housing blocked or carbonised

When the bearing housing is blocked or carbonised, the oil does not leave the turbocharger quickly enough. The oil therefore has to follow a different path, and presses the seals outwards on the turbine side. This usually results in the formation of blue smoke, due to contact between the oil and the high-temperature exhaust area.

Solution


Change the oil and replace the oil filter. Have the turbocharger repaired or replaced.

Crankcase ventilation malfunction

If the crankcase air exhaust is blocked, back pressure builds up in the oil drain pipe, preventing the oil from leaving the turbocharger quickly enough. The oil then has to follow a different path, and presses the seals outwards on the turbine side. This usually results in the formation of blue fumes, due to contact between the oil and the high-temperature exhaust area.

Solution


Proceed with cleaning, and refer to the motor manufacturer's manual.

Used piston rings and/or cylinder liners

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.

Engine wear

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.
Blue exhaust fumes

Blocked air intake between air filter and turbocharger

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes oil to leak from the turbocharger. With the pressure of the turbocharger, this oil leak reaches the combustion chamber, causing the oil to burn. In the worst case, the engine then runs on oil. Initially, this causes only blue exhaust fumes.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Air supply to turbocharger blocked

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes oil to leak from the turbocharger. With the pressure of the turbocharger, this oil leak reaches the combustion chamber, causing the oil to burn. In the worst case, the engine then runs on oil. Initially, this causes only blue exhaust fumes.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Blocked oil pipe

When the oil pipe is blocked, the oil does not escape from the turbocharger quickly enough. The oil therefore has to follow a different path, and presses the turbocharger seals outwards, on both the compressor and turbine sides. The oil then comes into contact with the high-temperature exhaust area via the turbine side of the turbocharger, resulting in excessive smoke formation.

Solution


Clean or replace if necessary.

Turbocharger bearing housing blocked or carbonised

When the bearing housing is blocked or carbonised, the oil does not leave the turbocharger quickly enough. The oil therefore has to follow a different path, and presses the turbocharger seals outwards, on both the compressor and turbine sides. The oil then comes into contact with the high-temperature exhaust area via the turbine side of the turbocharger, resulting in excessive smoke formation.

Solution


Change the oil and replace the oil filter. Have the turbocharger repaired or replaced.

Contaminated turbocharger compressor rating

The presence of impurities on the compressor side prevents the turbocharger from drawing in air freely. This creates a vacuum, which causes oil to leak from the turbocharger. With the pressure of the turbocharger, this oil leak reaches the combustion chamber, causing the oil to burn. In the worst case, the engine then runs on oil. Initially, this causes only blue exhaust fumes.

Solution


We recommend that you thoroughly clean the compressor side using a non-corrosive product and a soft brush. Then determine the cause of the contamination to ensure that it does not recur in the short term.

Air leak between intake manifold and cylinder head

An air leak can cause oil to leak from the turbocharger. With the pressure of the turbocharger, this oil leak reaches the combustion chamber, causing the oil to burn. In the worst case, the engine then runs on oil. Initially, this causes only blue exhaust fumes.

Solution


Replace damaged seals and check all fasteners thoroughly. Refer to the manufacturer's manual for further information.

Air leak between turbocharger and intake manifold

An air leak can cause oil to leak from the turbocharger. With the pressure of the turbocharger, this oil leak reaches the combustion chamber, causing the oil to burn. In the worst case, the engine then runs on oil. Initially, this causes only blue exhaust fumes.

Solution


Make sure you repair the leak by applying hose clips or replacing the defective parts. This will immediately improve the pressure supplied by the turbocharger.

Crankcase ventilation malfunction

If the crankcase air outlet is blocked, back pressure builds up in the oil drain pipe, preventing the oil from leaving the turbocharger quickly enough. The oil therefore has to follow a different path, and presses the turbocharger seals outwards, on both the compressor and turbine sides. The oil then comes into contact with the high-temperature exhaust area via the turbine side of the turbocharger, resulting in excessive smoke formation.

Solution


Proceed with cleaning, and refer to the motor manufacturer's manual.

Used piston rings and/or cylinder liners

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.

Engine wear

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.
Black exhaust fumes

Blocked air intake between air filter and turbocharger

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes the turbocharger pressure to drop. As the turbocharger pressure is too low, the fuel is no longer fully burnt due to the lack of air during combustion. This causes the smoke to blacken.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Blocked air intake between turbocharger and intake manifold

In this situation, the turbocharger reaches its normal speed, but the pressure it produces is not transmitted to the combustion chamber. The engine therefore receives insufficient pressure from the turbocharger, and the fuel is not fully burnt, due to the lack of air during combustion. This causes the smoke to blacken.

Solution


We advise you to check the air ducts carefully. Make sure that no dirt remains when you refit them. If there is serious damage to the pipes, replace them immediately. Failure to do so could damage the turbocharger.

Air supply to turbocharger blocked

A blocked filter/air intake prevents the normal intake of air by the turbocharger. This creates a vacuum, which causes the turbocharger pressure to drop. As the turbocharger pressure is too low, the fuel is no longer fully burnt due to the lack of air during combustion. This causes the smoke to blacken.

Solution


We recommend that you replace the air filter element, following the car manufacturer's instructions. Also check the air filter housing containing the filter, as well as the air duct leading to the turbocharger. If oil is leaking from the turbocharger, clean the pipes as well.

Camshaft and/or timing belt incorrectly adjusted

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.

Mouth catalyst

When the exhaust manifold is blocked, the amount of exhaust gas collected by the turbocharger is insufficient. As the turbocharger is driven by the exhaust gases, it cannot reach the required speed. The engine therefore receives insufficient pressure from the turbocharger, and the fuel is not fully burnt, due to the lack of air during combustion. This causes the smoke to blacken.

Solution


We recommend that you clean and, if possible, replace the catalytic converter. Refer to the manufacturer's manual for further information.

Intake manifold

In this situation, the turbocharger reaches its normal speed, but the pressure it produces is not transmitted to the combustion chamber. The engine therefore receives insufficient pressure from the turbocharger, and the fuel is not fully burnt, due to the lack of air during combustion. This causes the smoke to blacken.

Solution


We advise you to check the intake manifold thoroughly. Clean the intake manifold thoroughly and make sure that no dirt remains when you refit it. If the manifold is seriously damaged, replace it immediately. Failure to do so could damage the turbocharger.

Exhaust manifold

When the exhaust manifold is blocked, the amount of exhaust gas collected by the turbocharger is insufficient. As the turbocharger is driven by the exhaust gases, it cannot reach the required speed. The engine therefore receives insufficient pressure from the turbocharger, and the fuel is not fully burnt due to the lack of air during combustion. This causes the smoke to blacken.

Solution


We recommend that you clean and, if possible, replace the exhaust manifold. Refer to the manufacturer's manual for further information.

Contaminated turbocharger compressor rating

Contamination on the compressor side can cause slight damage to the compressor impeller, resulting in reduced engine power. This may be due to impurities entering the turbocharger via the air filter or leaking pipes. This damage causes insufficient air to be drawn into the turbine, resulting in low pressure. As the turbocharger pressure is too low, the fuel is no longer burnt completely due to the lack of air during combustion. This causes the smoke to blacken.

Solution


We recommend that you thoroughly clean the compressor side using a non-corrosive product and a soft brush. Then determine the cause of the contamination to ensure that it does not recur in the short term.

Air leak in the duct between the air filter and the turbocharger

An air leak means a loss of pressure from the turbocharger upstream of the combustion chamber. The engine therefore receives insufficient pressure from the turbocharger, and the fuel is not fully burnt due to the lack of air during combustion. This causes the smoke to blacken.

Solution


Plug the leak by applying hose clips or replacing damaged areas.

Air leak between intake manifold and cylinder head

An air leak means a loss of pressure from the turbocharger upstream of the combustion chamber. The engine therefore receives insufficient pressure from the turbocharger, and the fuel is not fully burnt due to the lack of air during combustion. This causes the smoke to blacken.

Solution


Replace damaged seals and check all fasteners thoroughly. Refer to the manufacturer's manual for further information.

Air leak between turbocharger and intake manifold

An air leak means a loss of pressure from the turbocharger upstream of the combustion chamber. The engine therefore receives insufficient pressure from the turbocharger, and the fuel is not fully burnt due to the lack of air during combustion. This causes the smoke to blacken.

Solution


Make sure you repair the leak by applying hose clips or replacing the defective parts. This will immediately improve the pressure supplied by the turbocharger.

Exhaust gas leak between cylinder head and exhaust manifold

If the exhaust gases leak before entering the turbocharger, this means that the amount of exhaust gas collected by the turbocharger is insufficient. As the turbocharger is driven by the exhaust gases, it cannot reach the required speed. The engine therefore receives insufficient pressure from the turbocharger, and the fuel is not fully burnt due to the lack of air during combustion. This causes the smoke to blacken.

Solution


Replace damaged seals and check all fasteners thoroughly. Refer to the manufacturer's manual for further information.

Exhaust gas leak between the exhaust manifold and the turbocharger

If the exhaust gases leak before entering the turbocharger, this means that the amount of exhaust gas collected by the turbocharger is insufficient. As the turbocharger is driven by the exhaust gases, it cannot reach the required speed. The engine therefore receives insufficient pressure from the turbocharger, and the fuel is not fully burnt due to the lack of air during combustion. This causes the smoke to blacken.

Solution


Replace damaged seals and check all fasteners thoroughly. Refer to the manufacturer's manual for further information.

Incorrectly adjusted fuel pumps or atomisers

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.

Intermediate cooler blocked or faulty

In this situation, the turbocharger reaches its normal speed, but the pressure it produces is not transmitted to the combustion chamber. The engine therefore receives insufficient pressure from the turbocharger, and the fuel is not fully burnt, due to the lack of air during combustion. This causes the smoke to blacken.

Solution


We advise you to check the intercooler thoroughly. Make sure that no dirt remains when you refit it. If the intercooler is seriously damaged, replace it immediately. Failure to do so could damage the turbocharger.

Used piston rings and/or cylinder liners

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.

Plugged exhaust pipe or silencer

When the exhaust manifold is blocked, the amount of exhaust gas collected by the turbocharger is insufficient. As the turbocharger is driven by the exhaust gases, it cannot reach the required speed. The engine therefore receives insufficient pressure from the turbocharger, and the fuel is not fully burnt due to the lack of air during combustion. This causes the smoke to blacken.

Solution


We recommend that you clean and, if possible, replace the exhaust pipe and silencer. Refer to the manufacturer's manual for further information.

Engine wear

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.
Engine goes into emergency mode

Ill-adjusted or damaged atomisers

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Carry out an adjustment, and replace any damaged parts if necessary.

Variable geometry turbine control ring

A deposit of soot on the control ring of the turbocharger variable jets is likely to hinder their operation. They may therefore catch or remain in a certain position, causing insufficient or excessive turbocharger pressure. The engine will then go into emergency mode. Switch the engine off and then on again: everything should return to normal. However, this malfunction will occur more and more, causing further damage to the turbocharger.

Solution


Check and/or replace the magnetic valve and sensor. Replace the turbocharger if necessary.

Faulty turbocharger/intake manifold pressure sensor

The pressure measured is insufficient if the turbocharger pressure sensor malfunctions. This means that the system will require additional turbocharger pressure, which the turbocharger cannot provide because it is impossible to increase the engine speed above that of the high gears. The vehicle's power is therefore insufficient, which usually activates an emergency programme.

Solution


Replace the turbocharger pressure sensor.

Soot deposits on the variable geometry turbine

Soot deposits on the turbocharger's variable jets can interfere with their operation. They may therefore catch or remain in a certain position, causing insufficient or excessive turbocharger pressure. The engine will then go into emergency mode. Switch the engine off and then on again: everything should return to normal. However, this malfunction will occur more and more, causing further damage to the turbocharger.

Solution


Replace the turbocharger
High ratio power loss

Ill-adjusted or damaged atomisers

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Carry out an adjustment, and replace any damaged parts if necessary.

Faulty turbocharger/intake manifold pressure sensor

The pressure measured is insufficient if the turbocharger pressure sensor malfunctions. This means that the system will require additional turbocharger pressure, which the turbocharger cannot provide because it is impossible to increase the engine speed above that of the high gears. The vehicle's power is therefore insufficient, which usually activates an emergency programme.

Solution


Replace the turbocharger pressure sensor.

Mouth catalyst

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


We recommend that you clean and, if possible, replace the catalytic converter. Refer to the manufacturer's manual for further information.

Faulty air flow meter

The air flow meter no longer reacts normally when its sensors are contaminated. As a result, the amount of fuel injected is insufficient, with a non-negligible drag on the engine during acceleration. This is the only problem caused by this cause.

Solution


Clean or replace if necessary

EGR valve contaminated

When the EGR valve is contaminated, the amount of exhaust gas returned to the engine's combustion chamber is insufficient. The air/fuel ratio is therefore inappropriate, resulting in a loss of power in high gears. This is the only problem caused by this cause.

Solution


Clean or replace if necessary

Plugged exhaust pipe or silencer

When the exhaust manifold is blocked, the amount of exhaust gas collected by the turbocharger is insufficient. As the turbocharger is driven by the exhaust gases, it cannot reach the required speed. The engine therefore receives insufficient pressure from the turbocharger, resulting in a loss of power.

Solution


We recommend that you clean and, if possible, replace the exhaust pipe and silencer. Refer to the manufacturer's manual for further information.
Power loss when the engine is hot

Ill-adjusted or damaged atomisers

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Carry out an adjustment, and replace any damaged parts if necessary.

Damaged turbocharger vacuum line

When the vacuum lines leading to the turbocharger are damaged, the turbocharger variable washer is not moved into the closed position. As a result, the turbocharger has insufficient pressure and the vehicle's power output is low.

Solution


Replace the vacuum pipe

Mouth catalyst

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


We recommend that you clean and, if possible, replace the catalytic converter. Refer to the manufacturer's manual for further information.

Incorrectly adjusted fuel pumps or atomisers

This possible cause has no other connection with the turbocharger as far as this symptom is concerned.

Solution


Refer to the engine manufacturer's manual for more information.
Excessive turbocharger pressure

Variable geometry turbine control ring

A deposit of soot on the turbocharger's variable jets is likely to hinder their operation. They may therefore catch or remain in a certain position, causing insufficient or excessive turbocharger pressure. If the variable jets remain locked in the closed position, the turbocharger pressure is excessive.

Solution


Check and/or replace the magnetic valve and sensor. Replace the turbocharger if necessary.

Soot deposits on the variable geometry turbine

Soot deposits on the turbocharger's variable jets can interfere with their operation. They may therefore catch or remain in a certain position, causing insufficient or excessive turbocharger pressure. If the variable jets remain locked in the closed position, the turbocharger pressure is excessive.

Solution


Replace the turbocharger

Pressure relief valve blocked

When the overpressure valve or the overflow valve is blocked in the closed position, the turbine runs continuously at an excessive speed. Unloading is therefore no longer possible. The pressure in the turbocharger is therefore excessive, and engine power falls.

Solution


Test, adjust and replace atomisers if necessary