as i took the heat shield off my exhaust manifold the other day, i had to unplug what i think was an 02 sensor plug. so i unplugged it, plugged it back in.. and now i have a CEL on. got it check out and as i thought... 02 sensor. is there anything harmful that could happen if i dont replace this?

 

Yea, your gas mileage will probably be affected as the o2 sensor basically tells the ecu the A/F ratios, and to either add more gas or lessen it. Now, if you don't ever fix it, yea potential problems could arise. If you are saying something like that you won't have the money for the next two weeks, then you should be fine. Just don't ignore it forever.

 

What year and CEL code?

 

u coulda threw the code if u cranked it up with the o2 unplugged

 

 

right on, i reset the ecu and wa la!
no code.
thanks to everyone who posted