2002 Nissan Xterra P0138 Error: Bank 1 Sensor 2 Secondary HO2S Circuit High Voltage Issue
Hello, I'm experiencing a 'Service Engine Soon' error code P0138 on my 2002 Nissan Xterra. This code relates to the secondary oxygen sensor (HO2S) circuit in Bank 1 Sensor 2. Can anyone explain what this means and what potential causes might exist? I recently had a new torque converter installed—could this installation have disturbed the wiring or sensor connection, leading to the P0138 fault?
The P0138 code indicates a problem with either the post-catalyst oxygen sensor, its circuit, or the electrical connection. It's possible that during the transmission replacement, the sensor wiring or harness was disturbed or damaged. I recommend taking your vehicle back to the shop that performed the transmission work for a thorough inspection of the sensor and related circuits. Good luck—please update us on the outcome.