Mercedes-Benz W204 injector faults and injector replacement
W204 CDI: how can I tell a faulty or leaking injector?
Symptoms can be mild: poor starting, uneven or knocking idle, lack of power after a long drive or a smell of burnt rubber. An injector fault does not always show in fault codes, so a workshop confirms it from the injector correction values.
How can I suspect a leaking injector at home?
Hold the throttle steady at about 2000 rpm and release it. If there is a step or a hesitation as the revs fall, the injector may be leaking. A leaking injector lets diesel into the cylinder, and if it continues for long it can damage the pistons, so it is worth sorting out in good time.
What should be noted when replacing an injector?
The fault is usually fixed by replacing the injector, and the cause depends on the engine and the car. When the high-pressure lines are removed, new lines should be fitted. The fuel lines are bled until no more air bubbles come out. The plastic connectors on the return line can break easily.