2003 c230k CEL Headache - Benzworld.org

GTP/Kompressor_driver · 07-13-2008, 02:08 PM

Hi

I have been hunting the vast interweb to try and explain what is the deal with my c230k. It started 2 months ago when I got a check engine light driving home from work. I took it to the dealership to get it scanned and I was told that the downflow 02 sensor needed to be replaced. At first I was kinda of surprised by this because my car only has 44,000 miles on it. Well after the part was replaced, I was CEL free for about a month. Again when I was driving home from work the CEL came back on. I used a obd 2 scanner to check for codes. This time it was a p0130. I replaced the upflow 02 sensor and now have 3 codes dropping. p0130, p0137, and p0170. From reading other examples of 02 sensor codes, should I assumed that my MAF is the next logical step in trying to solve this problem. I don't want to start replacing random components now. Any suggestions would be greatly appreciated.

**Buellwinkle** · 07-13-2008, 06:46 PM

It's could be the MAF. First reset the codes, unplug it and drive around for a while. If it runs better then it was the MAF. You will get a MAF code like a P0100, that's OK, it's because it's disconnected but if you get the old codes like P0170 and such then it wasn't the MAF.

GTP/Kompressor_driver · 07-13-2008, 10:25 PM

Thanks for the reply. I will give it a try. One thing I did not mention is that the car does not seem to drive differently. I don't notice much of a power loss if any. However there have been situations where I am driving and the car stutters. This happened at a stop and during driving. The stuttering though hardly happens and occurs randomly. I have yet to have a stuttering problem with the newly installed up flow 02 sensor.
What I am trying to figure out is that since the p0170 is a pending code and not active now then it is not the code I should worry about? Since this code is only pending then this leads me to believe that I am not near any tolerance (ie running too rich or lean). Therefore why would I be dropping 02 sensor codes as active codes? This is my first merc so does it take a few driving cycles for the codes to clear themselves? Do I need to go to the dealer to basically have them hook up a STAR, clear the codes, and tell the ECU to relearn with the new 02 sensors?

Thanks

**Buellwinkle** · 07-14-2008, 11:26 AM

You can read and clear codes using an OBD2 scanner. They range in price from about $50 on up depending on features and the simplest ones can read/reset codes, the fancy ones log sensor output and give you code definitions.