P0170 and P0173 error codes - PeachParts Mercedes-Benz Forum

rcend · #1 12-10-2006, 02:46 AM

1999 C280, 95K miles.

I have pulled the P0170 and P0173 error codes from the computer. At the same time, while I was driving with these codes, I didnt notice anything out of the ordinary until the car began to occasioanlly surge (a little below red line) for a small gas pedal depression, and a driver's side cylinder misfire (Cylinder 4,5,6) error code. I noticed this one, it bucked terribly.

I am tempted to replace the MAF, I have done some cleaning with a MAF cleaner, but no change. I have replaced spark plugs, air filter, and fuel filter. One thing that has me worried is that the passenger and driver's side floor is getting warmer than usual. Could the catalytic converters be warming up too much?

Any ideas will be helpful.

mpolli · #2 12-11-2006, 12:55 AM

My information on this is just from reading the posts here over the last couple of years. Having said that, the 170 code usually means new MAF is needed. No you can't clean it. Well you can, so then when you replace it it will be clean when you throw it away... Misfires are usually code 300 or 302. These are sometimes from the spark plug connector(s). I suppose whatever the trouble is could cause a rich condition that would heat up the cat. Hopefully the experts will chime in now!

Mike

blackmercedes · #3 12-11-2006, 08:44 AM

When the fuel trim is maxed, it can cause a misfire condition. Read the adaptation values and you'll get a much better diagnosis. I'm willing to bet the fuel trim is maxed at 1.32 and you need a new Air Mass Meter.

The flip side (not as frequent, but still happens) is that it's adapating the other way and the fuel pressure regulator is shot.