Chip2011

I have an intermittent check engine light due to code p0402. I know this is related to EGR system but not certain where to start. Any help would be appreciated. I have cleaned the EGR valve but didn't go any deeper. When I clear the light, it comes back in about a week. Any ideas? 2008 E320 Bluetec 94,000 miles.

konigstiger

Check condition of seal ring (part # 0259973448 about $2) if fine you may need to replace valve - current part # 6421401860 to comparison shop, parts.com $312.

Chip2011

I haven't seen a seal ring on the EGR. (maybe that is the problem!!!). Is this where the EGR attaches to the engine. There are two screws that hold the EGR onto the engine. I can also contact the parts guy at MB.

konigstiger

#76 in diagram

Chip2011

Thanks so much!!! This clears it up perfectly. I'll check it out.

Chip2011

I cleaned up the EGR; reset the check engine light and then the check engine returned (about 40 miles after reset) and then went away after driving around 60 miles. Does anyone know why it would go out after coming on? Any ideas on this would be great to hear.

I have since driven the car over 5000 miles with no check engine light. I'm thinking problem is fixed for now.

2008 e320 bluetec
97,000 miles.

avbar

Did you ever get this problem resolved? I've got the same exact car and same exact problem.

Chip2011

I cleaned the EGR, new seals, reset the light and it hasn't come back.

avbar

Thanks Chip,

I've cleaned my EGR, but the CEL keeps coming on and going off randomly. About every other day. The car runs perfectly by the way.

I haven't "reset" the light. I don't have a scanner or anything. Do you think that the CEL needs to be cleared, or will it clear itself if the problem is fixed?
Or should I run by some auto shop/dealer/autozone and have them clear it to see if it returns?

Any thoughts?

ozusa

Once it has run the Exhaust Gas Recirculation monitor successfully, it should (may ?), turn off the light. That said, a simple code reader and clearer doesn't have to cost much and can help with troubleshooting your next issue. It won't replace StarDiad/DASXentry, but it's helpful.

If you want to know more about OBD-II codes and such, then Haynes has an excellent book "OBD-II & Electronic Engine Management Systems". Haynes Techbook 10206, ISBN 1 56392 612 1. It is written for the technically-minded, lay-person. I got mine at Pep Boys.