P0036: HO2S Heater Control Circuit (Bank 1 Sensor 2)

What does P0036 mean?

The heater circuit for the oxygen sensor behind the bank 1 catalyst is malfunctioning. Its purpose is to bring the downstream sensor to operating temperature for emissions monitoring. The engine may feel unchanged because this sensor is not the primary upstream mixture-feedback sensor.

Generic OBD-II definition: HO2S Heater Control Circuit (Bank 1 Sensor 2). Confirm applicability in your vehicle service information.

Common causes

• Open downstream heater element
• Broken heater feed or return
• Damaged exhaust-area wiring

Symptoms

• Check engine light
• Usually little or no change in drivability
• Catalyst monitor may not complete

Diagnostic focus

The downstream heater prepares the catalyst-monitoring sensor for operation after startup. A heater failure alone does not prove the catalytic converter is inefficient.

Can I keep driving with P0036?

Severity: Low If the engine runs normally and the light is steady, arrange emissions-system diagnosis. Stop for a flashing light or severe roughness; those symptoms need separate urgent attention.

If the check engine light is flashing or the car runs badly, stop driving and have it checked.

Typical fixes

• Allow the exhaust to cool before inspecting wiring
• Verify fused power and the heater return, then compare heater resistance with specification.
• Repair wiring or replace the correct sensor only when the fault is confirmed

Sources & review

• OBD-Codes.com: P0036
• TroubleCodes.net: generic code definitions

Definitions and diagnostic background checked 2026-11-06. Generic guidance, not a substitute for the service procedure for your exact year, engine, and transmission.