OBD-II code · Powertrain (generic, extended)
P2251 O2 Sensor Negative Current Control Circuit (Bank 1 Sensor 1)
The negative current control line (Vs−) of the wide-band lambda sensor on bank 1 sensor 1 is open or out of range. Used as the virtual ground reference for the Nernst cell.
Is it safe to drive with P2251?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyVs− line open
- PossibleWide-band sensor failed
Symptoms
- Check engine light on
- Increased fuel consumption
- Possible rough idle or hesitation
- Failed emissions test
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–2 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Oxygen Sensor Wideband, Oxygen Sensor Wiring
Related codes
- P2237O2 Sensor Pumping Current Circuit (Bank 1 Sensor 1)
- P2243O2 Sensor Reference Voltage Circuit (Bank 1 Sensor 1)
- P224EAlternative Fuel Tank Shutoff Valve A Control Circuit Low
- P224FAlternative Fuel Tank Shutoff Valve A Control Circuit High
- P2250O2 Sensor Reference Voltage Circuit High (Bank 2 Sensor 1)
- P2252O2 Sensor Negative Current Control Circuit Low (Bank 1 Sensor 1)
- P2253O2 Sensor Negative Current Control Circuit High (Bank 1 Sensor 1)
- P2254O2 Sensor Negative Current Control Circuit Low (Bank 2 Sensor 1)
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.