Hi, I recently replaced my O2 sensors (both front ones) and after about 2 weeks my CEL came on. I pulled the codes and got 0304 (Knock Sensor) and 0308. 0308 seems like the O2 sensor. Which O2 sensor is causing the problem? The one on the passenger side or the one in the middle? Please help me as I need to pass CA smog and I can't if the CEL keeps coming on. Thanks!

0308
Diagnostic Trouble Code 0308 points to a problem with the Engine Control Module Closed Loop Logic for the Right Bank. The right cylinder bank is also called the rear bank. It is cylinders 1,3,5.

DTC 0308 is detected when the closed loop control function for the right bank does not operate even when the vehicle conditions meet the criteria (engine at normal operating temperature, etc.). Possible causes include ...
- Harness or connectors (The sensor circuit is open or shorted.)
- a defective Front Heated Oxygen Sensor sensing element.
- a defective Front Heated Oxygen Sensor heater.

 

Front Right Bank O2 sensor is the O2 sensor in the y-pipe closest to the firewall (upstream of the catalytic converter).