Check engin light came on, i scanned it and code # P0173 = fuel trim / malfuntion came up. i erased code and 8 miles later light was back on! all this and car runs great! scanned it again same code.
does anybody know what (fuel trim) is or means? also what part died?
thanx, BB

To get a more accurate diagnosis, you'll need to read the adaptation values. With "high" numerical values (1.32) odds are you need a new Air Mass Meter. With "low" numerical values (.67) you are probably in need of a new fuel pressure regulator. Fuel trim indicates the FI system compensating for either a rich or lean condition and has become unable to do so because the problem has reached the limits of the system to compensate. Don't operate the vehicle for an extended period in this condition as it can damage the catalytic converter.

Replace the potential offending part with a known-to-be-good example and re-read adaptation values.

With your particular model/year, I would bet on the AMM. Do you have any operating symptoms?

BTW, if you don't believe me, try a search. This code has been covered, probably, hundreds of time. Very common.

__________________
John Shellenberg
1998 C230 "Black Betty" 240K

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