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
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References
sae:J2012