Check Engine Code
P0131
O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1)
What P0131 means
P0131 means the upstream oxygen sensor on Bank 1 is reporting a voltage below the expected range for an extended time — indicating a persistently lean exhaust or a failed sensor.
Symptoms
- Check engine light
- Rough idle or hesitation
- Reduced fuel economy
- Possible hesitation under load
Likely causes (most common first)
- Exhaust leak upstream of the sensor
- Vacuum leak (intake boot, PCV, EVAP)
- Failed O2 sensor
- Short to ground in the O2 signal wire
- Contaminated sensor (silicone, coolant, oil)
Can I keep driving?
Medium — drivable but fix soon
Typical repair cost
DIY fixes can start near $30 (parts only). Shop repairs for P0131 typically run up to $300 depending on the underlying cause and vehicle. Start with the most common cause — Exhaust leak upstream of the sensor — before throwing parts at it.
Recommended parts & tools for P0131
Most common fix for P0131:
Oxygen (O2) sensorCompare the parts and tools that pair with AXLY:
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