P0131 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
The upstream (before the catalytic converter) oxygen sensor, Bank 1 Sensor 1, stays at low voltage, which reads as lean.
Common causes
- Exhaust or vacuum leak
- Faulty sensor
- Signal wire shorted to ground
Symptoms
- Check engine light
- Possible hesitation
What to check
- Look for exhaust leaks upstream of the sensor
- Check fuel trims
- Inspect wiring
Manufacturers may add their own detail to generic codes. If your vehicle shows a different description for P0131, follow the service information for that make and model.
Related codes
- P0130 O2 Sensor Circuit (Bank 1 Sensor 1)
- P0132 O2 Sensor Circuit High Voltage (Bank 1 Sensor 1)
- P0133 O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)
- P0134 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)
- P0135 O2 Sensor Heater Circuit (Bank 1 Sensor 1)
- P0136 O2 Sensor Circuit (Bank 1 Sensor 2)