P0036
Low SeverityHO2S Heater Control Circuit (Bank 1, Sensor 2)
Emissions System
What Does P0036 Mean?
The heater circuit for the downstream (post-cat) O2 sensor on bank 1 has failed. This sensor monitors catalytic converter efficiency.
Common Fix
Replace downstream O2 sensor bank 1
Estimated Cost (DIY)
$25 - $80
Symptoms
- ⚠️Check engine light
- ⚠️Failed emissions test
- ⚠️No noticeable driveability issues
- ⚠️Possible false P0420 code
Common Causes
Failed O2 sensor heaterlikely
Wiring damage from exhaust heatpossible
Blown fusepossible
Connector corrosionpossible
How to Diagnose P0036
- 1Check O2 heater fuse
- 2Inspect downstream sensor wiring for heat damage
- 3Measure heater resistance
- 4Replace sensor if heater open-circuit
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Frequently Asked Questions
- Does P0036 affect performance?
- No, the downstream O2 sensor only monitors the catalytic converter. You will not notice any driveability change.
- Can P0036 cause P0420?
- Yes, a faulty downstream sensor can give false P0420 readings. Fix P0036 first and see if P0420 clears.