2000 C230K (W202) 116K - CEL goes on and off, code reads P0170 Self Adaptation at Limit Fuel Trim Malfunction. Car runs fine, gas mileage is unchanged. Original O2 sensors. No obvious vacuum leaks. Any ideas?

Maf.

Check the adaptation values and see if it's compensating rich or lean. Odds are it's the Air Mass Meter, but the fuel pressure regulator also fails. If you are adapting to 1.32, then the AMM is the likely culprit. .67 would mean it's probably the pressure regulator.

Both are common causes for the P0170 code.

Replace the possible offending part with a "known good one" and recheck the adaptation values.

__________________
John Shellenberg
1998 C230 "Black Betty" 240K

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Independent changed maf but also read code P0130 today. Is the 02 sensor bad or was this code a result of a bad maf? Did I just waste $414 on the maf? By the way, is that a decent price for the Bosch item?