OBD-II code guide
P0151 Oxygen Sensor Circuit Low Voltage Bank 2 Sensor 1
P0151 means the upstream oxygen sensor voltage on bank 2 is lower than expected.
What it means
Bank 2 may be running lean, or the oxygen sensor circuit may have a low signal fault.
Common symptoms
- Check engine light
- Hesitation
- Rough idle
- Poor fuel economy
- Lean running symptoms
Likely causes
- Vacuum leak on bank 2
- Exhaust leak
- Low fuel pressure
- Oxygen sensor fault
- Wiring issue
First checks
- Check fuel trims by bank.
- Inspect vacuum and exhaust leaks.
- Confirm bank 2 sensor 1 before replacing.
- Look for P0174 or MAF codes.