P22BCO2 Sensor Reference Voltage Performance (Bank 2 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
- P22BC concerns the plausibility of the Nernst-cell signal of the wide-band probe fitted after the bank 2 catalyst. The leads test fine, yet the cell voltage that the controller uses as its set point drifts, reacts slowly or cannot be held, so the computed oxygen value loses credibility. No maker documents this code publicly, and none publishes a limit for its upstream relative P2248 either. The usual reasons are physical: an aged cell whose resistance has climbed well above the nominal 300 ohms of a Bosch LSU 4.9, deposits from oil or coolant, or a weak heater. CARB requires a downstream sensor to remain good enough to judge the catalyst. Siblings: P22BB open, P22BD/P22BE low/high, P22AF bank 1. The lamp lights and catalyst results may be withheld.
- What you may notice
- Check engine light
- Bank 2 downstream oxygen reading lags behind or is offset from the other sensors
- Catalyst monitor for bank 2 does not complete
- Likely causes
- LikelyAged downstream wide-band sensor on bank 2 with raised Nernst-cell resistance
- PossibleOil, coolant or additive deposits on the sensing element
- RareHeater output too low to keep the cell at working temperature
- RareContact resistance in the Nernst-cell terminal
- 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.