P2256O2 Sensor Negative Current Control Circuit High (Bank 2 Sensor 1)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2256 means the negative current control line (reference ground) of the bank 2 upstream wide-band sensor reads too high, typically a short to battery or heater voltage. No manufacturer publicly documents P2256 with thresholds. Ford's OBD summaries send a short to battery on any wide-band sensor line to P0152 and reserve P2254 for the open line; VW's 2014 books also list only P2254 for this circuit. CARB requires fuel-control sensors to be checked for circuit continuity and out-of-range values, with separate codes where feasible. P2253 is the bank 1 counterpart, P2255 the low-side fault, P2254 the open circuit. A short to voltage can damage the sensor or the interface, so the wiring should be checked before a new sensor is fitted.
- What you may notice
- Check engine light
- Higher fuel consumption
- Repeat failure of a new sensor if the wiring short remains
- Likely causes
- LikelyReference ground wire shorted to heater supply or battery voltage
- PossibleInternal short in the wide-band sensor
- RareFault in the sensor interface of the ECM
- 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: €80 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.