P0130O2 Sensor Circuit (bank 1 sensor 1)
What it means
The ECU sees an electrical fault in the oxygen sensor circuit, bank 1 sensor 1. The upstream sensor (before the catalyst) is what the ECU uses to correct the mixture.
Symptoms
- Check engine light
- Higher fuel consumption
- Possibly a rough idle or failed emissions test
Common causes
- Open or shorted signal or reference wire
- Corroded connector (often from exhaust heat or water)
- Failed oxygen sensor
- Exhaust leak near the sensor
What to check first
- Graph the sensor voltage at 2,500 rpm: a narrowband sensor should switch between about 0.1 and 0.9 V
- Check the wiring where it runs near the exhaust
- Check for exhaust leaks upstream of the sensor
Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.