Rep Power: 197

a while ago a posted a thread about my check engine light and my gas cap. well after a few days, the light went off so i forgot about the problem, assuming it somehow fixed itself.

few days ago, the light came back on. i had the code read by my mechanic and it was an o2 sensor in the exhaust. i planned to check on monday if it was covered by honda since my car was recently purchased. however today the light went back off. is it possible that my o2 sensor is just malfunctioning and not totally broken? should i be worried and get it checked anyway or just forget about it till the light comes back on?

 
Rep Power: 234

Cats go bad gradually. Could be the cat, could be the O2 sensor, could be something else making the sensor read bad. There are two circuits in the sensor, could be either one. Do you have the specific code? That would help a lot. It might be something simple we could help you with.

 
Rep Power: 812

if its the primary sensor, it can start to get "slow response" when its too old, causing engine light to come and go. its def time to change it since it affects how the engine runs. but its not an immediate danger. 01-03 will have cheap sensor, 04-05 has expensive.

 
Rep Power: 197

The mechanic said it's sensor #2, but I forgot to ask for the specific code. He gave me an estimate of 138$ to replace. Looks like it's time to fork out more money during the already expensive xmas holiday.

Thanks guys

 
Rep Power: 812

you can def wait on sensor 2. all it does is tell the ecu whether the cat is working. has no bearing on engine performance at all.

 
Rep Power: 0

I had the exact same symptoms about 1 year ago. Mine is a 2004 coupe. I bought a code reader and it read P0139, 2nd O2 sensor slow response. The CEL went on and off intermittently. I replaced the O2 sensor and erased the code. It never came back. I know there is a Service Bulletin on some VIN for a ECU software update for that particular code. That wasn't my case.

The fix is simple but a bit expensive.

 
Rep Power: 197

Thanks!