ok so i have changed my 02 sensor 3 times sense i did a dpfi to mpfi swap and head gasket replacement and i set the ignition timing and it still keeps going bad i drove the car for 31 miles and my check engine light came on and the ecu shows a code 1 for 02 sensor when i set the ignition timing the way honda wants it i started the car and let it warm up in till the cooling fans came on and then i jumped the ignition jumper plug and adjusted the distributor to the red tick mark but the check engine light doesn't come on when i jump it i need help to set it right on my 1991 civic and is this way it keeps going bad im lost and pissed off cuz im tired of getting new o2 sensor if any one can help me that would be great thanks

 

Just because the code trips, it doesn't mean the sensor is bad, it means the sensor is telling the ECU that it's readings are outside specification.

There could be other reasons that its fouling apart from ignition timing. Running rich, Map sensor giving a bad reading due to bad vacuum lines, fouled spark plugs, poor spark...

 

What brand o2?

 

I think I have the same problem. Check Engine keeps coming on for the o2 sensor which I already replace. I just ignore it now.

 

its a denso from autozone