OBD2 help
 

so my 01 s4 had two codes which caused a cel, the codes were 1113 and 1131. According to the reader it was one of my o2 sensors, i spent the day yesterday replacing that and cleared the cel, it popped back on today and when i checked it again 1131 was the only code. Does anyone have any idea what that code is for the reader wont say which this one is for. Thanks

There are two O2 sensors. It must be the other sensor. Good luck