P2195 - O2/A-F Sensor Signal Stuck Lean (B1S1)

Upstream O2/A-F sensor signal stuck lean (bank 1).

Code Overview

Upstream O2/A-F sensor signal stuck lean (bank 1).

Common Causes

• Vacuum/exhaust leak
• Fuel delivery issue
• Sensor fault
• Injector/pressure issue

Symptoms

• Lean surge or hesitation
• Poor cold-start fueling correction
• High positive fuel trims
• Check engine light with fuel-control symptoms

Diagnostic Steps

1. Check fuel trims
2. Inspect vacuum/exhaust leaks
3. Verify sensor response on scan tool
4. Check fuel pressure if needed
5. Review fuel trims at idle and cruise
6. Inspect for intake or exhaust leaks before replacing the sensor
7. Verify upstream sensor response on the scan tool
8. Check fuel pressure and injector performance if the lean condition is real

Likely Repairs & Cost Guides

Use test results to confirm the fault before pricing the repair.

Related OBD Codes

Browse the closest code-family pages when the same fault pattern often shows up nearby.

Next Steps

Move from the code to a diagnosis path, then into repair pricing once the fault is confirmed.