2006 GMC Yukon 5.3L Engine P0155 Oxygen Sensor Heater Circuit Fault
The check engine light has activated on my 2006 GMC Yukon 4x4 with a 5.3L V8 engine. The diagnostic trouble code displayed is P0155, indicating a heater circuit malfunction for the oxygen sensor in Bank 1 (heated oxygen sensor). I want to confirm whether this sensor is located before or after the catalytic converter. Can someone clarify its position and provide guidance on troubleshooting steps? Thank you for your help.
P0155 refers to a heater circuit malfunction in the oxygen sensor located in Bank 1, Sensor 1 — this is situated on the passenger side of the engine, before the catalytic converter. Before replacing the sensor, it's essential to inspect the wiring harness and electrical connections. Also, verify that the relevant fuse is intact. If the issue is indeed with the oxygen sensor, it's recommended to obtain a genuine OEM part from the dealership rather than using aftermarket replacements.