P0036
Low SeverityHO2S Heater Control Circuit (Bank 1, Sensor 2)
Emissions System
P0036 — Instant Answer
HO2S Heater Control Circuit (Bank 1, Sensor 2)
Severity: LOW SEVERITY
Meaning: The heater circuit for the downstream (post-cat) O2 sensor on bank 1 has failed. This sensor monitors catalytic converter efficiency.
Safe to drive? Usually yes with caution, but confirm root cause before long trips.
Estimated repair cost: $25 - $80
Most common causes:
- 1. Failed O2 sensor heater (35-45% of cases)
- 2. Wiring damage from exhaust heat (10-25% of cases)
- 3. Blown fuse (10-25% of cases)
- 4. Connector corrosion (10-25% of cases)
Symptoms
- ⚠️Check engine light
- ⚠️Failed emissions test
- ⚠️No noticeable driveability issues
- ⚠️Possible false P0420 code
Related Symptoms
Common Causes
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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Related Codes
Low voltage in the downstream O2 sensor heater on bank 1. The heater element has likely burned out.
The heater in the downstream O2 sensor on bank 1 has failed.
The oxygen sensor heater circuit on the upstream (pre-cat) sensor of bank 1 has a fault. The heater gets the O2 sensor to operating temperature quickly for proper fuel trim.
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.
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Author & Review
Written by AllOEMManuals Editorial Team. Reviewed by ASE-certified technicians and updated with factory-reference checks for fitment-sensitive steps.
This guide was drafted with AI assistance and reviewed for accuracy by a human editor.
Last updated: 2026-05-07