Hey guys. I have a quick question about O2 sensors and smog checks. My rear O2 sensor went out and is throwing a CEL. I was told by a smog tech that I would fail immediately just because of the CEL. However, when I reset the ECU it takes about 2 days before the CEL comes up again. My question is, can I reset the ECU right before the smog and pass or will they still be able to see that the O2 sensor is bad? I know that this sounds cheesy and the rear O2 sensor is an easy fix but I just need to smog for registration purposes and I'm probably the lazyest person you'll ever meet.

thanks in advance for any help.

 

If the O2 sensor is out, your fuel mixture might not be correct either and that could make you fail the test even if the CEL is not on.

Don't worry about the laziness. A mechanic would gladly take your money if you don't feel like doing the work.