Code
P0131
Emissions
Oxygen sensor circuit low voltage — Bank 1 Sensor 1
The upstream oxygen sensor voltage is stuck low, indicating a very lean signal or sensor fault.
Advertisement
Most likely causes
- Faulty O2 sensor
- Exhaust leak before the sensor
- Wiring short
- Lean fuel condition
Symptoms you may notice
- Check engine light
- Worse economy
Checks to run
- Check O2 switching live
- Inspect for exhaust leaks
- Test wiring
Tools you may need
OBD-II scanner
Multimeter
Always diagnose before replacing. Codes share symptoms; confirm the cause with measurements before buying parts.
Related codes in Emissions
P0420