P0036
HO2S Heater Control Circuit Bank 1 Sensor 2
Fuel & air metering (O2 sensor)
Generic OBD-II
Medium
What it means
P0036 means the ECM found a fault in the heater control circuit of the bank 1, sensor 2 oxygen sensor — the downstream sensor after the catalytic converter. The built-in heater brings the sensor up to operating temperature quickly; when its circuit fails, the sensor reads late or not at all. The engine still runs fine, but emissions monitoring is degraded.
Medium
Can I keep driving? Safe to drive — the engine runs normally, but the downstream oxygen sensor can't warm up properly, so emissions monitoring is affected and it will fail an emissions test.
Common symptoms
What you'll notice
- Check-engine light on
- Often no noticeable change in how the car drives
- Failed or incomplete emissions readiness monitor
- Slightly reduced fuel economy in some cases
Common causes
Most likely first
- Failed heater element inside the bank 1 sensor 2 (downstream) oxygen sensorLikely
- Blown fuse or open in the heater power feedCommon
- Damaged wiring or corroded connector at the sensorCommon
- Poor ground or loose connection in the heater circuitLess often
- Faulty engine control module (ECM), rarelyLess often
How to diagnose & fix
Work through it in order
- Locate the bank 1 sensor 2 oxygen sensor (downstream, after the catalytic converter).
- Check the heater circuit fuse and the sensor connector for corrosion or damage.
- Measure the sensor's heater resistance and supply voltage against spec.
- Repair wiring or replace the oxygen sensor if the heater element has failed.
- Clear the code and drive a full cycle to confirm the monitor completes.
FAQ
Quick answers
Is it safe to drive with P0036?+
Yes. This affects the downstream sensor's heater, not engine operation, so the car drives normally. Fix it before an emissions test, and it can cost you a little fuel economy.
Can I just clear P0036?+
It comes back once the ECM tests the heater circuit again, unless the sensor or wiring is repaired.
Related codes
Often seen with P0036
Read & clear P0036 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX