Engine and gearbox (P)
P0038: Oxygen Sensor Heater Circuit High Voltage
The heater control circuit for the oxygen sensor on bank 1, sensor 2, is showing a higher voltage than expected. This usually indicates a short to the power supply.
Checked by a licensed car technician · last reviewed 30 September 2026
Symptoms
- Check engine light on
- Increased fuel consumption
- Failed emissions test
Common causes
- Heater wire shorted to supply
- Connector pins corroded
- Supply wire pinched against power source
How to check it yourself
- Inspect the oxygen sensor wiring for damage
- Check the connector for corrosion
- Test the voltage at the sensor connector
Can I keep driving?
The car can still be driven, but it should be repaired soon to avoid increased emissions.
General guidance, not a professional inspection. Confirm faults with measurements before buying parts, and use a qualified mechanic for brakes, steering, fuel leaks, airbags, and other safety-critical work. Terms and disclaimer