Sexi2k

I had a P0141 (o2 sensor malfunction) prior and I fixed that today. Erased the code with my OBD2 scanner, unplugged the negative battery terminal for 15 minutes, drove ~10 miles, the CEL is still here but no codes are read. Any ideas?

Midnightdennis

Found this piece of advice Billman gave in an older but similar thread:

”Start the car cold in the morning, drive around local 5 minutes, shut it off (this will complete a "trip").

Start it back up, take it on the highway and set the cruise at 60 for 3 minutes (this will complete a second "trip", and make two-trip monitors "ready" like the air pump monitor).

Example: if you start the car cold, and drive it 10,000 miles without shutting it off, the two-trip monitors will never run and you will fail inspection It's all about parameters...not miles.”

Hfreak

^^^ I believe that the procedure you are quoting is to "ready" the monitors for smog testing and not to clear a visible CEL.

Car Analogy

If you clear a code with a scan tool, then there is no reason to disconnect battery. That is counter productive.

That erases all the learned parameters in the ecu that help your car, your engine, run its best. It also erases any cels, so its a lame way to clear codes if you don't have a scan tool. But if you have a scan tool, battery disconnect trick is stupid.

What to do now? Just drive the car, know that it won't run its best until it relearns everything. Drove like Normal, so it relearns how you drive, and in what conditions. Meanwhile, see if the code comes back.

Next time, clear cel, drive car. See if code returns.

Sexi2k

Thanks, I suspected it was something like this but didn't know the proper procedure. Will do this in the morning tomorrow.

On my scan tool, there were no DTC codes but some I/M were not in ready status. I remember that cat converter was not yet in ready. Don't know if it will clear the CEL but its worth a shot since no codes are thrown.

Thanks for the tip.

Midnightdennis

The point I was trying to make was to put some drive cycles in. Resetting the ECU/using a scan tool/disconnecting the battery isn’t always the final step.

Sexi2k

I did the local and highway 2-trip cycle drive and it did help ready all my monitors except for EVAP. However, CEL is still here. No codes found. Any other suggestions?

Midnightdennis

Some good alternatives/info found on this page: https://www.s2ki.com/forums/s2000-un...-code-1060194/

Sexi2k

I've already read through every post regarding P0141 and ways to fix it but no luck. I'm not sure the CEL is related to the previous codes I had - all of which I fixed. Knock sensor, cat converter, and o2 sensor.

Sexi2k

I suspect it may be a bad ECU. Going to remove and inspect for visual damage.