Common Checks
- Check for vacuum leaks and exhaust leaks before replacing the sensor.
- Inspect sensor wiring and connector condition.
- Compare fuel trims and sensor response during enrichment.
Diagnostic trouble code
P2195 Bank 1 Sensor 1 Oxygen Sensor Signal Biased/Stuck Lean
The upstream oxygen sensor signal on bank 1 appears stuck lean or biased lean.
Fuel Trim & Mixture CodesCommon Repairs
- Repair vacuum or exhaust leaks.
- Repair oxygen-sensor wiring faults.
- Replace a biased upstream oxygen sensor after confirming the engine is not actually lean.
Mustang Notes
- This code can overlap with P0171; diagnose the air/fuel cause first.
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.