Mercedes C Klasse Diesel Rough Idle Issue Resolved

My 2010 Mercedes C Klasse diesel is acting up. The check engine light is on, and the engine is running rough, especially when idling. Sometimes it even stalls, which is super annoying. When I accelerate, it feels like the engine is jerking. I scanned it and it's showing a defective fuel pressure sensor. Could a bad connection or plug really cause all this? I'm hoping it's not the fuel pump or fuel injector because that would really be expensive. It's hard to believe that a simple electrical issue messes with the fuel economy that much, or even causes an engine misfire.

4 comment(s)

I had something similar happen with my C Klasse. It also turned out to be related to the fuel system, though I can’t say for sure if it was the exact same sensor. Are you sure the sensor itself is bad? Maybe double check the wiring first.

That’s interesting. When you say similar, do you mean similar symptoms or the same error code? And how exactly did you check the wiring? Just visually or with a multimeter?

Symptoms were similar: rough idle, stalling, and the check engine light. The error code pointed to fuel issues. I didn't check the wiring myself, to be honest. I took it to a workshop.

Thanks for the info. I appreciate it. I'll check the wiring as best I can, but I think I’ll probably end up taking it to a shop too. It turns out it was indeed a faulty connection at the fuel pressure sensor. The plug was corroded. They cleaned it up and replaced the connector. Cost me 95€, but it’s running smooth again.

Join the discussion now: