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Mercedes S Klasse EGR Valve Problem

My 2009 Mercedes S Klasse with a gasoline engine is having issues. The check engine light is on, power is down, it smokes, runs rough, drinks fuel, and jerks. There's also a hissing sound when I accelerate. I think it's the EGR valve. Any ideas before I start repairs?

4 comment(s)

Sounds like EGR valve failure. The symptoms point to it being jammed. The hissing could be exhaust leaking. Have you checked the EGR valve for carbon buildup? What codes are you getting?

I haven't pulled the codes yet, but I will tomorrow. Where should I look for carbon buildup on the EGR valve? If it is buildup, can I clean it, or should I just replace the EGR valve?

Cleaning might be temporary given the mileage. The valve mechanism could be worn. Remove the EGR valve and inspect the valve seat and pintle for carbon deposits. I'd lean toward replacing it for a reliable emissions test and proper running. Replacement is likely the better long-term solution for optimal recirculation.

Thanks! The codes confirmed it was the EGR valve. I replaced it. The workshop charged me 355€ including parts and labor. It runs great now, no more smoke or jerking, and the check engine light is off! Hopefully, it will pass the emissions test. Thanks for the help!

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