2005 W203 C320 OM642 CDI Poor cold start

[Ereinz]

Like in video, any ideas?
It now takes about 3-4seconds before the engine starts with a puff of white/grey smoke (smells of burnt diesel). When the engine is warm, it starts instantly.

 

[alexanderfoti]

Very likely to be Glow plug(s) or relay or both.

 

[Ereinz]

I read the error codes and there is
P0670 and P2270

 

[malcolm E53 AMG]

The glow plug relay is a weak point on the OM642 of that era but certainly worth testing each glow plug to see whether one or two are faulty first

 

[alexanderfoti]

Those two codes relate to glow plug and O2 sensor out of range.

 

[Oldspanners]

Have a look at the video it's on a Jeep Grand Cherokee same OM642 and a lot of good detail on fault finding.

 

[quinnj3]

Certainly sounds like glow plug issues. Try operating your ignition 2 or 3 times before attempting to start to see if that helps any.

I had an issue last year where the car was fault code free but in cold weather it would turn over a few times before starting and then run rough for ~10s or so. After much faffing about and expense from mis diagnoses by my mechanic I eventually replaced the glow plug relay module at a cost of £100 supply only from Mercedes. 5 mins work and the car was like new.


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[Ereinz]

Glow plug relay changed. Problem solved.