to have to re-set the CEL more than once? The reason I ask, i have had the pesky codes 2-3-1, 2-2-1, pop up. After sniffing around I decided to put in a new O2 sensor and stuck a working used MAF from the pick/pull in it. Following the new sensor, I drove it about 1/2 mile and the light popped on again with the same codes. I re-set the light and called it a night to try and figure out what to do next. I also checked for air leaks. There were none I could find.

Today, my son took the car out for errands. He said it ran better and there have been no CEL's pop on. Does the computer ECU have to "re-learn" and go a few miles to stop throwing codes after changing out an O2 sensor?

Just wondering.
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93' 240 Classic Wagon 220K & 92' 740 Wagon Regina/Rex 90K

Yes, the ECU takes some time to relearn. This applies to other repairs as well.

Don't get discouraged if the codes pop up again. The computer sometimes doesn't forget and old codes can keep popping up.

The computer in my 90 still remembers the code for a bad intake manifold gasket that was repaired about 3 years ago. I was constantly pulling the battery cables off, but eventually the light would come back on. However in a recent post there was a suggestion to pull the #6 fuse (I believe it is #6 but please do a search to verify) and that will fix it. Don't know if this works since my car was recently sold, but it is certainly worth a try.....:)

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Bessie - 95 855 GLT Sportwagon; 93 854 GLT; Inga - 90 244 DL 300k, gone but not forgotton