Engine and gearbox (P)
P0036: HO2S Heater Control Circuit Fault
This code indicates an electrical fault in the heater control circuit for the oxygen sensor located after the catalytic converter on bank 1. The heater helps the sensor reach operating temperature quickly.
Checked by a licensed car technician · last reviewed 30 September 2026
Symptoms
- Check engine light on
- Increased emissions
- Poor fuel economy
Common causes
- Heater element open
- Blown heater fuse
- Faulty wiring or connections
- Failed oxygen sensor
- Faulty control module
How to check it yourself
- Inspect and replace the heater fuse if blown
- Check wiring and connections for damage or corrosion
- Test the oxygen sensor heater element for continuity
- Inspect the control module for faults
Can I keep driving?
The car can still be driven, but it may have increased emissions and reduced fuel efficiency.
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