OBD-II · Engine and powertrain (P)
P2273
Oxygen sensor signal stuck rich bank 2 sensor 2
What it means
The downstream (after the catalytic converter) lambda sensor on bank 2 keeps reporting a rich mixture when the ECU expects it to change. It can be a real rich mixture or a sensor or wiring fault. Confirm bank 2's location in the engine's service information.
Symptoms
- engine warning light
- usually no change in how the car drives
- may fail the emissions part of the roadworthiness test
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | faulty or contaminated downstream sensor |
| 02 | genuinely rich running |
| 03 | signal wire short to voltage |
| 04 | wiring or connector fault |
What to check, step by step
- 01Fix any fuel-trim, misfire or upstream sensor codes first
- 02Check the exhaust for leaks around the downstream sensor and the flex pipe
- 03Watch the sensor in live data during overrun fuel cut: a healthy narrowband sensor drops below about 0.2 V
- 04Check the signal and ground wiring and the connector
- 05Replace the sensor if it does not respond