Originally posted by maximus
Ok OVP is out of the question I replace it this afternoon dealer charge me $76 took it out right in the parking lot replace it in 2 secs , the car started ok but after 2 mins the rough idling started again It took the car 5 mins to come back to normal and now on the way home my check engine light came on , could the check engine light have something to do with my rough idling or what usually make the check engine light come one on a MB
If you have a check eng light , the on board self diagnostics has detected a fault in the system . That means a code has been tripped and will point you in the right diagnostic direction..
The code chart will show which system/part is suspect.
Off hand , I would suspect a sticking egr valve or bad o2 sensor
as they both come into play after warm up. But the code will tell that for sure.
Don't change parts til you get the code. There are 32 fault code that will trip the light . Do a search on how to pull the codes
and how to make the tool to DIY or go get it scanned.
When you have that info, I will be happy to tell you what the chart fault suggest.