P2251O2 Sensor Negative Current Control Circuit/Open (Bank 1 Sensor 1)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2251 points to an open negative current control line, i.e. the reference or virtual ground (VM on Bosch, COM on NTK) of the bank 1 upstream wide-band sensor. Ford detects it on Bosch parts by a sensor voltage stuck in a narrow band, or by a reference-current pulse that still moves lambda; NTK chips report the break directly. GM's 2005 V6 and Saab's 2010 9-5 look for 1.47-1.53 V with cell resistance above 570 ohms and exhaust below 900 °C (Type B); VW's 2014 Passat book uses a 950-ohm limit. GM calls it low reference circuit. Bulletins: ECM reflash for the 2020-22 Corvette (22-NA-019) and 2013-14 Dart 2.4 (18-011-14), new sensor for 2016-18 Range Rover TDV6 (LTB01191) and 2025 Wrangler (23-019-25). P2254 is bank 2, P2252/P2253 low/high.
- What you may notice
- Check engine light
- Higher fuel consumption from open-loop fuelling on bank 1
- Possible rough running or failed emissions test
- Likely causes
- LikelyBroken reference ground wire or pushed-back pin between sensor and ECM
- PossibleInternal open circuit in the wide-band sensor
- RareEngine software that sets the code falsely (reprogramming for some models)
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €0 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.