So for the past month or so I have been driving my car with the check engine light on (secondary o2 sensor), so i really haven't worried about it. But i was driving last night in 20 degree weather and my car backfired extremely loud at 2800 rpm and then my check engine light went off. My first though was "oh **** that couldn't be good" but then i noticed my CEL was gone so I'm not sure should i have it checked out or just leave it alone. What should i do?

Its a 99 Integra b20 (p8r head) running a stock ls ecu
only mods to the engine are intake and rs*r exhaust

Thanks in advanced for replies

 

I have the same thing on my B20 integra. I did a lot of research and found that with the B20 it always has a check engine light on cause its looking for the fuel tank pressure sensor (I think) It may not be the same thing...

 

no i dont think so because my CEL was always for my o2 sensor and i have driven this motor without a CEL for a year and a half but then the CEL came on sometime over the summer and im running a ls ecu

 

does the car perform like it should?

 

yeah its preforms as well as it always has except for a hesitation between 2500rpms and 2800 rpms at 1/3 throttle

 

i would def say u need a new o2 sensor. i donno why the light went off but the backfire is more than likely related to the 02 sensor. change it and see what results u get

 

Check and see if you have any other codes first. If you are misfiring you could get multiple codes. I know these are two TOTALLY different things, but when my Rover misfires, the code for that comes up, plus, system too lean, plus a code for the o2 sensors (it has 4 of them) when in reality, it just my plugs or wires. You might be getting a code for the 02 sensor because of something else that is associated with it.