P2AC8Charge Air Cooler Coolant Temperature Sensor B Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2AC8 sets when charge air cooler coolant temperature sensor B delivers an electrically valid value that makes no sense for the situation, for example after a long engine-off period when every temperature in the engine bay should have converged, or when it fails to change while the loop pump runs and the cooler heats up. No maker documents this exact check publicly; Ford and GM only publish thresholds for sensor A (P00DE to P00E2). Besides a drifting sensor, the low-temperature circuit itself can trigger it: low coolant, trapped air or a weak electric pump make the reading real but unexpected. Check level and bleeding first, then compare B in live data with sensor A and with the engine's own coolant reading. Hard limits of the signal are P2AC9 and P2ACA.
- What you may notice
- Check engine light on, often only after several drives
- Sensor B reads clearly different from sensor A after a cold soak
- Higher intake air temperature under load
- Likely causes
- LikelyLow coolant level or air trapped in the low-temperature loop
- PossibleSensor B drifting out of its characteristic
- PossibleElectric charge air cooler coolant pump weak or not running
- RareControl module software needing an update
- 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 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.