TorqueMech OBD Code Guide
P0131 - O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
An oxygen sensor circuit issue was detected.
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Inspect ignition coils
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Code Overview
An oxygen sensor circuit issue was detected.
Common Causes
- Failing upstream oxygen sensor on bank 1 sensor 1
- Exhaust leak ahead of the sensor
- Wiring fault or poor terminal contact in the sensor circuit
- Actual lean-running condition on bank 1
Symptoms
- Check-engine light with lean fuel trims
- Rough idle or hesitation
- Poor fuel economy or drivability complaint
Diagnostic Steps
- Check fuel trims, misfire codes, and exhaust leaks before condemning the sensor
- Inspect the bank 1 sensor 1 harness near the exhaust for damage
- Watch upstream sensor switching and voltage behavior on the scan tool
- Verify the circuit and confirm the engine is not actually running lean
Repair Difficulty
Moderate
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Next Steps
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