OBD-II code · Powertrain (generic)
P0031 HO2S Heater Control Circuit Low (Bank 1 Sensor 1)
O2 sensor heater control circuit on bank 1, sensor 1 reports low voltage. Likely shorted to ground or open in the heater control wire. The heater warms the sensor element to operating temperature (~600 °C); without it the sensor stays inactive in closed loop and the ECM cannot trim mixture.
Is it safe to drive with P0031?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyHeater control wire shorted to ground
- PossibleHeater element internally shorted
- Less likelyConnector pins corroded - high contact resistance
Repair at a glance
- Difficulty
- Easy
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–1.5 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Oxygen Sensor Heater, Sensor Wiring
Related codes
- P0030HO2S Heater Control Circuit (Bank 1 Sensor 1)
- P0037HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
- P0051HO2S Heater Control Circuit Low (Bank 2 Sensor 1)
- P0057HO2S Heater Control Circuit Low (Bank 2 Sensor 2)
- P002EB Camshaft Profile Actuator A Control Circuit Low Bank 2
- P002FB Camshaft Profile Actuator A Control Circuit High Bank 2
- P0032HO2S Heater Control Circuit High (Bank 1 Sensor 1)
- P0033Turbocharger Bypass Valve Control Circuit
- P0034Turbocharger Bypass Valve Control Circuit Low
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.