Fault code: 57089 SCANIA

Error identification:

The torque on the front bank, cylinders 1-3, is too high in comparison with the rear bank, cylinders 4-6.

Cause:

One of the solenoid valves for fuel volume or injection timing is causing incorrect engine torque for one bank. This may either be because the cylinders on the front bank are receiving too much fuel or because the cylinders on the rear bank are receiving too little fuel.

If the engine accelerates, the fuel volume solenoid valve on the front bank is probably stuck in a position where too much fuel is provided to the cylinders.

If the engine output drops, the fuel volume solenoid valve on the rear bank is probably stuck in a position where too little fuel is provided to the cylinders.

If the engine output drops and there is also white smoke, the injection timing solenoid valve on the rear bank is probably providing too little fuel. The injection is then so late that no combustion takes place.

The fault can also be caused by leaking O-rings on the unit injectors.

The fault code can be triggered by air in the fuel system or low fuel pressure. In such cases, the fault code is only generated occasionally.

Air can become mixed into the fuel e.g. during refuelling, fuel starvation, suction leakage or fuel filter renewal and there is no risk of the engine running at high revs.

Notes:

The engine runs very unevenly, because the engine speed is limited to between 500-850 rpm via the fuel shut-off valve.

It is likely that fault code 135 low fuel pressure will also be generated. If this is the case, troubleshoot according to 135. These torque variations cause the engine to run unevenly and can be so small that the driver or mechanic does not notice them.

The air mixture can also cause the engine to run unevenly, and the torque variations which trip the fault code. The problem does not need to be fixed.

Action:

If the engine has accelerated, renew the solenoid valve for the fuel quantity on the front bank.

If the engine has lost power, renew the solenoid valve for the fuel quantity on the rear bank.

If the engine has lost power and is emitting white smoke, renew the solenoid valve for the injection timing on the rear bank.

If leaks are suspected on unit injectors, renew all O-rings.

Check that the cover and O-ring seal properly.

If the fault code is only generated occasionally, the cause may be air mixed into the fuel. No action required.