OBD-II · Engine and powertrain (P)
P0036
Oxygen sensor heater control circuit bank 1 sensor 2
What it means
The ECU detects a fault in the circuit it uses to switch the heater of the downstream (after the catalytic converter) lambda sensor on bank 1.
Symptoms
- engine warning light
- slightly higher fuel consumption and emissions after a cold start
- usually no change in how the car drives
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | failed heater element inside the sensor |
| 02 | blown fuse or missing power feed |
| 03 | wiring damage near the exhaust |
| 04 | connector corrosion |
| 05 | ECU driver fault |
What to check, step by step
- 01Check the fuse and relay that feed the lambda sensor heaters
- 02Inspect the connector and wiring along the exhaust
- 03Measure the heater resistance at the sensor and compare with specification
- 04Check the heater control wire between the sensor and the ECU for opens and shorts
- 05Replace the sensor if the heater element is faulty