Common Checks
- Inspect the oxygen-sensor connector, heater fuse, and heater wiring.
- Check for chafing or melted insulation near the exhaust.
- Verify heater circuit continuity.
Diagnostic trouble code
P0155 Bank 2 Sensor 1 Oxygen Sensor Heater Circuit
The upstream bank 2 oxygen-sensor heater circuit is not operating as expected.
Oxygen Sensor & Heater CodesCommon Repairs
- Repair damaged heater wiring.
- Replace the oxygen sensor if the heater element has failed.
Mustang Notes
- Routing changes during exhaust work can create intermittent heater faults.
Model-Year Applicability
Listed for 1996 and newer traditional gasoline Mustang pages in this first-pass catalog. Engine, calibration, and Ford-specific codes may narrow that range as more service data is added.