P2B8AIntake Air O2 Sensor Circuit High Voltage Bank 1
- 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
- P2B8A is the mirror image of P2B89: the bank 1 intake oxygen sensor delivers a voltage above its valid window. On a wide-band element this usually comes from a signal wire touching a supply or the heater feed, from an open ground or reference return that lets the input float upward, or from water inside the connector. A value that high would mean more oxygen than fresh air can hold, so the module cannot derive EGR dilution from it and falls back to a model or stops recirculation. No manufacturer publishes P2B8A. Ford's patent DE102014220034A1 learns the sensor's zero point while no exhaust is recirculated, the reference against which an implausibly high reading stands out; US8775011B2 separates sensor faults from a leaking EGR valve. P2B89 is the low side, P2B88 the general circuit fault.
- What you may notice
- Check engine light on
- EGR switched off, possibly slightly higher fuel consumption
- Intake oxygen reading on the scan tool above the fresh-air value
- Likely causes
- PossibleSignal wire shorted to a supply or to the heater feed
- PossibleOpen ground or reference return lead of the sensor
- PossibleWater in the sensor connector
- RareInternal sensor fault
- 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: €60 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.