1999 Nissan Maxima P0138 and P0325 Fault: Which Sensor to Replace First?
I own a 1999 Nissan Maxima with the Check Engine Light illuminated. My OBD2 scanner is showing both P0138 (Rear Oxygen Sensor Malfunction) and P0325 (Knock Sensor Failure). I'm unsure whether to replace the rear oxygen sensor first and see if the P0325 code clears, or prioritize replacing the knock sensor. Additionally, is the rear oxygen sensor difficult to replace? Any guidance on troubleshooting this combination of fault codes would be greatly appreciated.
P0325 is common in approximately 7 out of every 10 Nissan vehicles scanned. However, the P0325 code alone typically does not trigger the MIL (Malfunction Indicator Lamp). Therefore, it's recommended to start by replacing the faulty rear oxygen sensor and monitor whether the P0325 code clears after the replacement.