Mercedes-Benz OM 904-926 LA BlueTec Operating Instructions Manual page 94

Troubleshooting
92
Problem
Engine braking effect is
poor.
Fuel consumption is
too high.
Engine cuts off too
early (maximum engine
speed cannot be
reached).
Engine gets too hot
(according to coolant
temperature gauge).
Charge current indica-
tor lamp does not light
up while the engine is
not running.
Charge current indica-
tor lamp lights up when
the engine is running.
Possible causes/consequences and M Solutions
There is an engine brake flap malfunction or a fault in the actua-
tion.
X
Carry out a function check/visual check.
X
Consult a qualified specialist workshop.
Connection points (unit pump - line and fuel injectors) are leaking
X
Have a qualified specialist workshop check for leaks.
X
Misfiring: have the engine checked at a qualified specialist
workshop.
Electronic engine speed control unit is faulty or parameterised
incorrectly.
X
Consult a qualified specialist workshop.
There is not enough coolant in the cooling system.
X
Top up, bleed ( Y page 76)
Coolant temperature sensor or display is faulty.
X
Replace sensor or display.
Poly-V-belt is damaged.
X
See "Replacing the poly-V-belt" (
Fan does not switch on correctly.
X
Consult a qualified specialist workshop.
Radiator is dirty on inside or choked with limescale; radiator is very
dirty on outside.
X
Clean and remove limescale.
Thermostat is faulty.
X
Check and replace as necessary.
X
Consult a qualified specialist workshop.
Lamp is defective or supply line is interrupted.
X
Replace lamp or repair interruption.
Poly-V-belt is too loose.
X
Check belt tensioner for proper functioning.
Y page 97).