P2AC7Charge Air Cooler Coolant Temperature Sensor B Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2AC7 is the general circuit fault of the second coolant temperature sensor in the low-temperature loop that serves a water-cooled charge air cooler. Where two sensors exist, one usually sits at the cooler inlet and the other at its outlet, so the module can judge how much heat the cooler removes; in GM's 2025 diesel table, sensor A measures the water entering the cooler. No manufacturer publishes a description of P2AC7 itself. The code covers faults that cannot be classified as clearly low or clearly high, such as a signal the module rejects as invalid; those two extremes belong to P2AC9 and P2ACA. CARB requires circuit checks for every such input. The driver may notice the warning lamp and, on some engines, reduced boost as a precaution.
- What you may notice
- Check engine light on
- Implausible or missing value for sensor B in live data
- Reduced boost or power on some engines
- Likely causes
- LikelyLoose, corroded or coolant-contaminated sensor B connector
- PossibleChafed or broken wire between sensor B and the module
- PossibleInternally defective temperature sensor B
- RareFaulty sensor input or reference in the engine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €60 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.