Code
P0031
Emissions
HO2S heater control circuit low — Bank 1 Sensor 1
The O2 sensor heater circuit reads too low.
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Most likely causes
- Shorted heater wiring
- Faulty sensor
- ECM driver fault
Symptoms you may notice
- Check engine light
Checks to run
- Measure heater resistance
- Check for shorts
- Test the driver
Tools you may need
Multimeter
Always diagnose before replacing. Codes share symptoms; confirm the cause with measurements before buying parts.
Related codes in Emissions
P0420