Powertrain
generic / SAE
P0131
O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1)
The upstream oxygen sensor signal is fixed at a low voltage, indicating the ECU sees a continuously lean exhaust on bank 1 — or the sensor signal path is shorted to ground.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number1 / 31
Possible causes
- Exhaust leak upstream of the sensor high
- Signal wire shorted to ground medium
- Genuine lean running (vacuum leak, low fuel pressure) medium
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Inspection / repair
- Difficulty: medium
- DIY: possible
- Estimated cost: 60–400 €
- Estimated time: 0.5–3 h
- Component: oxygen sensor upstream
- Component: exhaust pipe pre cat
- MIL / check engine light
- emissions-relevant
- drive cycle required
Sources
References
sae:J2012