P22B1O2 Sensor Reference Voltage Circuit High (Bank 1 Sensor 2)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P22B1 is set when the reference voltage (Nernst-cell) line of the bank 1 downstream wide-band probe reads above its valid range. Because the cell delivers only a few hundred millivolts across about 300 ohms, any contact with the heater feed or another live wire overrides it. A cracked ceramic letting the heater circuit leak into the cell can do the same. No maker publishes this code with a threshold; for the upstream sensor, Ford and Saab already treat a voltage above 4.7 V as an open reference line, while Ford sends shorts to power to P0132. CARB demands detection of out-of-range values on air-fuel sensors behind the aftertreatment. P22AE covers the open, P22B0 the low reading, P22BE bank 2 and P2246 the upstream twin.
- What you may notice
- Check engine light
- Downstream oxygen reading stuck at a limit
- Likely causes
- LikelyNernst-cell wire shorted to the heater supply or another live wire
- PossibleCracked sensor ceramic leaking heater voltage into the cell
- RareFaulty sensor interface in the ECM or sensor module
- 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: €50 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.