OBD-II · Engine and powertrain (P)
P0055
Oxygen sensor heater resistance bank 1 sensor 3
What it means
The ECU measures a heater resistance for the third (further downstream) lambda sensor on bank 1 outside the expected range.
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 | aged or failing heater element |
| 02 | wrong or universal replacement sensor fitted |
| 03 | corroded connector adding resistance |
| 04 | wiring damage |
What to check, step by step
- 01Measure the heater resistance at the sensor connector, engine cold, and compare with specification
- 02Check the connector pins for corrosion that adds resistance
- 03Make sure the fitted sensor is the correct type for the car (a wrong or universal sensor can trigger this)
- 04Replace the sensor if the heater is out of spec