So my friend and I were replacing the header on my 00 si and the o2 sensor was stuck in the oem header so my friend sprays it with wd40, it comes out but after everthing is installed I get a check engine for the o2. We resetted the cel so its off for now. Could the wd 40 have messed up the o2 sensor? Should I look into replacing it? Thanks

 

How do you reset the check engine light? Mine came on about 6 months ago, when I was backing it up some ramps with the rear muffler removed. The car seems to run the same so I reckon there's nothing wrong with it, but the light is annoying.

 

I wouldn't worry about it unless it comes on again. I doubt the wd40 would mess with it. It's not like you sprayed down the entire o2 sensor with it. It could have just been your ecu getting used to the new header. I always reset the ecu whenever changing parts like this regardless if I am throwing a CEL or not.

To reset it, unplug the negative battery terminal. I leave mine unplugged for about 15 min or so (probably overkill). Re-connect the negative terminal. Now start the car w/out any aux stuff on (like A/C). Leave it in neutral and don't touch the gas pedal. Let it idle for about 15 min (probably overkill). Now turn off the car. That's it.

This way will reset all of your radio pre-sets with isn't a big deal to me. If you don't want it to reset them, there is a under-hood fuse you can pull instead of unplugging the battery.

 

:werd: for some reason pulling the ecu fuse didnt work on my 00 (worked on all previous cars tho). Oh and you can reset it with the obd2 code reader, my friend just happened to have one and thats how I did it.