Was driving to my brother's to have dinner this evening and saw the CEL pop up. Car still drove fine, no extra noises or out of the ordinary happenings.

After dinner I went to remote start the car and when it didn't start I remembered it won't remote start with the CEL on, so I went ahead and ran into Advance to get the code read. I took the code reader out to my car and it gave me P2A01. It has to do with the rear o2. I didn't write down the exact description, but a quick google search shows "HO2S Circuit Closed Loop (CL) Performance Bank 1 Sensor 2 (PCM)".

What was odd is it showed 3 codes. It showed the P2A01 twice, and it also showed a U1121 (Can't remember the U code 100%, but it said something along the lines of "Lost communication with Heater/Air Conditioning system"

I cleared the codes and the CEL didn't pop back up on the ride home.

My question is this, if it does pop back up am I looking at replacing the rear o2? Also what do you make of the other code? Anyone ever seen anything like that?