P0031
PowertrainOxygen Sensorlow severityHO2S Heater Control Circuit Low Bank 1 Sensor 1
What P0031 Means
The voltage in the Bank 1 Sensor 1 O2 heater circuit is lower than expected.
Symptoms
- Check Engine Light
- Extended warmup time
- Poor cold-start emissions
Common Causes
- Short to ground in heater circuit
- Faulty O2 sensor
- Corroded connector
Diagnostic Steps
- Test heater circuit voltage
- Check for shorts to ground
- Test sensor heater resistance
- Inspect connector
Where to start: Repair short or replace O2 sensor.
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