Powertrain, generic (extended)

P2AC7 Charge Air Cooler Coolant Temperature Sensor B Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Loose, corroded or coolant-contaminated sensor B connector
Chafed or broken wire between sensor B and the module
Internally defective temperature sensor B
Faulty sensor input or reference in the engine control module

Symptoms

  • Check engine light on
  • Implausible or missing value for sensor B in live data
  • Reduced boost or power on some engines

Repair estimate

DifficultyEasyDIY possible
Parts and labour€60–300
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

charge air cooler coolant temp sensor bwiring harnessecm

Related codes

P2AC8P2AC9P2ACAP2ACBP00DE

References: law.cornell.edu, gsi.ext.gm.com, fordservicecontent.com.