P2AC7 code meaning
Charge Air Cooler Coolant Temperature Sensor B Circuit
Powertrain system Generic code P2Axx codes Check engine light
What P2AC7 means
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.
P2AC7 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyEasy, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2AC7
- Check engine light on
- Implausible or missing value for sensor B in live data
- Reduced boost or power on some engines
Common causes of P2AC7
- Most likelyLoose, corroded or coolant-contaminated sensor B connector
- PossibleChafed or broken wire between sensor B and the module
- PossibleInternally defective temperature sensor B
- Less likelyFaulty sensor input or reference in the engine control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Charge air cooler coolant temp sensor bWiring harnessECM
What each part of P2AC7 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| A | Area: hybrid propulsion. |
| C7 | The exact fault in that area. |
What to do next
- Note P2AC7 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2AC7
What does P2AC7 mean?
P2AC7 means "Charge Air Cooler Coolant Temperature Sensor B Circuit". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P2AC7?
Drive gently and only to a workshop. With P2AC7 the car can go into limp mode (reduced power) to protect itself.
Will P2AC7 fail an emissions test?
Yes, it can. P2AC7 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2AC7 to fix?
Difficulty: easy. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2AC7 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.