robertsteel1

Mercedes Citan Diesel Engine Fault

My 2022 Mercedes Citan diesel has developed a fault. It has done 263925 km. The check engine light is on, and it feels like it has lost power. I'm also getting some smoke when accelerating, and the engine seems to be running rough. Fuel consumption is also up. I've noticed it jerks a bit when accelerating, and there's a loud hissing sound sometimes. Could this be the EGR valve? I'm worried about failing the emissions test.

4 comment(s)

Sounds like a dodgy EGR valve to me. The hissing points to a possible leak in the EGR system, which would definitely cause those symptoms. Is the rough idle all the time, or just when the engine is cold? A jammed EGR can cause havoc with your engine's recirculation. Think of it like trying to breathe through a clogged straw. Is it worse when the engine is cold or warmed up?

The rough running seems to be worse when the engine is cold, yes. What exactly does the EGR valve do anyway? And is it a big job to replace?

The EGR valve recirculates exhaust gases back into the engine to reduce emissions. If it's stuck open, especially when cold, it messes with the air/fuel mixture and causes a rough idle. Replacing it isn't usually a massive job, but it can be fiddly, and you might need some specialized tools. Given the symptoms and mileage, I'd suggest getting it checked out by a workshop. They can confirm the EGR valve is the issue and give you a proper quote for repair.

Thanks for the advice. I took it to a workshop, and they confirmed it was the EGR valve. The total automotive repair cost was 355€. Hopefully, this will fix the problem. Thanks again!

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