P0031
Low SeverityHO2S Heater Control Circuit Low (Bank 1, Sensor 1)
Emissions System
What Does P0031 Mean?
The O2 sensor heater circuit voltage is lower than expected on the upstream bank 1 sensor. Usually means an open circuit in the heater element.
Common Fix
Replace O2 sensor
Estimated Cost (DIY)
$30 - $100
Symptoms
- ⚠️Check engine light
- ⚠️Poor fuel economy when cold
- ⚠️Higher emissions
- ⚠️Slow O2 sensor response
Common Causes
Burned-out O2 sensor heaterlikely
Corroded connectorpossible
Broken wire to O2 sensorpossible
Blown heater fusepossible
How to Diagnose P0031
- 1Check fuse and relay for O2 heater
- 2Inspect connector for corrosion
- 3Measure heater element resistance
- 4Check for power and ground at sensor
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Frequently Asked Questions
- What does P0031 mean?
- P0031 means the upstream O2 sensor heater on bank 1 has low voltage — usually a burned-out heater inside the sensor.
- Is P0031 a cheap fix?
- Yes, O2 sensors cost $30-$100 DIY. It is one of the easier sensor replacements.