Powertrain, generic

P0EC3 A/C Refrigerant Temperature Sensor B Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P0EC3 stands for a sensor B signal pulled down toward ground. Because a thermistor of the NTC type lowers its resistance as it warms, the module reads a refrigerant temperature far above anything the system could reach. Typical culprits are a harness pinched against the body, water inside the plug or a sensor that has failed shorted. P0EC3 appears in no public manufacturer document. GM's evaporator sensor check on the 2012 Volt (P0537, below roughly 0.1 V, two trips) is the nearest documented model. On cars that cool the traction battery through the refrigerant loop the controller may restrict that cooling as well as the cabin A/C. Open-circuit side: P0EC2; sensor A equivalent: P0EBE.

Likely causes

Harness pinched against the body, signal shorted to ground
Water ingress in the sensor plug
Sensor B shorted internally

Symptoms

  • A/C compressor held off, cabin not cooled
  • Charging or driving power possibly limited if battery cooling depends on the loop

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–450
Time0.5–2 h

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

Parts involved

ac refrigerant temp sensor bhvac control modulewiring harness

Related codes

P0EC2P0EC1P0EC4P0EBEP0537

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