Threw an SES light about 300 miles ago, finally got the codes read at Autozone this morning....P0138 and P0139.

When my exhaust was installed, there was no bung to put the rear O2 sensor in, so it was just zip tied, and I was told if I chose to, I could have a hole welded for the sensor. I'm assuming that because it's just zip tied underneath the car, this is the reason that I threw these two codes which both pertain to the rear O2 sensor?

I cleared the codes at Autozone, but I'm assuming as long as I don't have the hole welded for the sensor that the codes will return - my question is this: does this O2 sensor affect anything crucial in terms of how the car runs? It's been almost 1500 miles since my exhaust was put on, and there's been no change in how the car runs.

Thanks for any information on these two codes.

 

I should also mention that my car is a 2000 SE Fed-Spec.

 

Nope, the rear O2 sensors are just used by the ECU to monitor catalyst efficiency. It won't affect drivability. Oh, and yes, the codes are for the bank 1 and 2 rear O2 sensors.