Mercedes-Benz OM 904-926 LA BlueTec Operating Instructions Manual page 92

Troubleshooting
90
Problem
Engine does not start
correctly.
Engine stops inadver-
tently.
Engine is in emergency
running mode.
Engine surges, vibrates
or runs irregularly.
Possible causes/consequences and M Solutions
Fuel is not resistant to cold.
X
Replace the fuel prefilter (
X
Replace the fuel filter (
X
Use winter fuel ( Y
Incorrect engine oil viscosity.
X
Alter the engine oil viscosity to the conditions of use
( Y page 47).
There is a malfunction in the engine control unit.
X
Read out the MR (engine control) unit, have it checked at a
qualified specialist workshop.
There are leaks or there is insufficient pressure in the low-pressure
fuel circuit.
X
Carry out a check for leaks (visual check).
X
Have the pressure tested at a qualified specialist workshop.
MR (engine control) unit is faulty (total failure).
X
Consult a qualified specialist workshop.
Power supply to the MR/ADM control units is interrupted or there
is a short circuit in the wiring.
X
Have the power supply checked at a qualified specialist work-
shop.
There are leaks or there is insufficient pressure in the low-pressure
fuel circuit or the fuel pump drive is faulty.
X
Check for leaks (visual check).
X
Have the fuel pressure tested at a qualified specialist workshop.
There is an interruption to the MR/ADM control unit's data flow.
X
Read out the control unit's fault memory.
X
Have it checked at a qualified specialist workshop.
Crankshaft sensor or TDC sensor (on camshaft gear wheel) is
faulty or the signal is missing.
X
Consult a qualified specialist workshop.
There is a malfunction in the fuel system.
X
Read out the fault code.
X
Have it checked at a qualified specialist workshop.
Y
page 68).
Y page 69).
page 52).