P22B0O2 Sensor Reference Voltage Circuit Low (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
- P22B0 says the reference voltage (Nernst-cell) line of the bank 1 downstream wide-band probe sits below its permitted range. On a Bosch LSU the Nernst cell is a high-impedance source that tolerates at most about 250 microamps, so a chafed wire touching ground drags it down at once. No maker documents this exact code publicly. Ford's upstream logic treats a cell voltage under 0.2 V as part of its open-circuit check and books shorted leads under P0131, which shows that makers split these faults differently. JLR lists the upstream analog P2245 in a bulletin on cracked sensors. P22AE is the open case, P22B1 the high one, P22AF the performance check, P22BD the bank 2 equivalent. The driver mainly sees the warning lamp.
- What you may notice
- Check engine light
- Downstream oxygen value implausible or unavailable
- Likely causes
- LikelyNernst-cell wire shorted to ground through damaged insulation
- PossibleInternal short in the downstream wide-band sensor
- RareMoisture in the connector creating a leakage path
- 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.