P0131
PPowertrainO2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
What does this code mean?
Severity : MediumP0131 indicates low voltage in the upstream oxygen sensor circuit on bank 1, sensor 1. This sensor measures oxygen in the exhaust so the engine control module can adjust the air fuel mixture. An abnormally low voltage makes the module believe the mixture is lean and upsets fuel control.
Symptoms
- Check engine light on.
- Higher fuel consumption.
- Rough idle or hesitation.
- Increased emissions.
Possible causes
- Faulty or aged upstream oxygen sensor.
- Wiring shorted to ground or damaged connector.
- Exhaust leak ahead of the sensor.
- A genuinely lean mixture from a vacuum leak or low fuel pressure.
- Engine control module fault, which is rare.
Diagnosis and repair
- Inspect the sensor wiring and connector, which are often exposed to heat.
- Check for exhaust leaks upstream of the sensor.
- Watch sensor voltage and fuel trims in live data.
- Check for vacuum leaks and verify fuel pressure.
- Replace the sensor if needed, clear the code and road test.
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Code
P0131
Category
Powertrain
Prefix
P
Standard
OBD-II / SAE J2012