Powertrain, generic (extended)

P2E7F A/C Compressor Control Module Internal Temperature Sensor B Circuit Low

Check engine lightOn
EmissionsNot relevant
Drive cycleRequired
Limp modeNo

P2E7F is the low-signal counterpart: sensor B inside the compressor control module reports a value below its valid band, which for a sensor with falling output means an impossibly hot reading. GM's comparable code on the compressor IGBT sensor is P0D78: the 2011 Volt fails above 274 °C, the 2018 and 2019 tables above 150 °C, with the compressor detecting the condition itself and passing it on over GMLAN, Type B. No manufacturer documents P2E7F. A short on the sensor path is the usual explanation. Genuine overheating of the power stage, for instance from too little refrigerant flow, should still be ruled out, because controllers like the one in a Mitsubishi Heavy Industries patent slow or stop the compressor when it runs too hot. The cold side is P2E7E.

Likely causes

Short circuit in the sensor B path on the control board
Measuring circuit of the compressor controller defective
Power stage genuinely overheating, e.g. low refrigerant charge

Symptoms

  • Compressor derates or shuts down for overheat protection
  • Air conditioning blows warm, battery cooling may be limited
  • MIL possible after two drive cycles depending on manufacturer

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–2,500
Time1–5 h

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

Parts involved

ac compressor cm internal temp sensor bac compressor module

Related codes

P2E7EP2E7CP2E7DP0D73P0D78

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, image-ppubs.uspto.gov.