P0031: O2 sensor heater circuit low (Bank 1 Sensor 1)
Drive carefully. Get it checked within a week or two.
Can I drive with P0031?
Yes, but drive carefully and get it checked soon. A sensor that helps set the fuel mixture is not warming up properly. The car usually runs, but fuel economy and emissions can get worse.
What does P0031 mean?
P0031 stands for HO2S Heater Control Circuit Low (Bank 1, Sensor 1).
Symptoms you may notice
- Drop in gas mileage by 10% to 15%
- Slight hesitation or sluggish response when accelerating
- Check engine light illuminated
How much does it cost to fix?
Repair costs for code P0031 depend on the specific underlying root cause, ranging from simple DIY checks to component replacement. The table below lists the most common causes and rough price ranges in USD:
- Short to ground in sensor heater wiring
- Internal short in the sensor heater element
- Blown fuse on heater power supply
- Faulty ECU heater driver circuit
What to do next
- Inspect the wiring harness for contact with the hot exhaust downpipe.
- Check heater fuse in the engine fuse box.
- Replace the upstream oxygen sensor.
Last updated: October 2026
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General guidance only, not a professional diagnosis. If the check-engine light is flashing, or the car is running rough, overheating or losing power, stop driving and get help.
About this code
Code P0031 is an electrical code indicating low voltage on the sensor heating circuit. It does not cause engine misfires, stalling, or transmission problems.