OBD-II · Engine and powertrain (P)
P0130
Oxygen sensor circuit bank 1 sensor 1
What it means
The upstream lambda sensor signal on bank 1 is invalid. Monitor criteria depend on sensor type and OEM: distinguish an electrical voltage fault from an in-range lean/rich signal before diagnosing mixture causes.
Symptoms
- engine warning light
- higher fuel consumption
- possible hesitation or uneven running
- may fail the emissions part of the roadworthiness test
Likely causes, most likely first
| No. | Cause |
|---|---|
| 01 | aged lambda sensor |
| 02 | exhaust leak before sensor |
| 03 | wiring fault |
| 04 | fuel mixture fault |
| 05 | sensor heater issue |
What to check, step by step
- 01Check the connector and wiring along the exhaust for melting, chafing or water in the plug
- 02With the engine fully warm, watch the sensor in live data (narrowband sensors switch roughly 0.1-0.9 V; wideband sensors read lambda near 1.00)
- 03Look for exhaust leaks before the sensor (manifold gasket, cracked flex pipe)
- 04Check the signal and ground wires for continuity and shorts back to the ECU
- 05Replace the sensor with the correct OE-type part if the wiring is good