Powertrain, generic · Hybrid propulsion

P0A02 Motor Electronics Coolant Temperature Sensor A Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

The signal voltage of the coolant temperature sensor in the electronics loop sits below its valid window. Because the sensor is an NTC thermistor, a low voltage means an implausibly hot reading, typically a short to ground. GM uses P0A02 on the 2013 Two-Mode hybrid Tahoe, Yukon, Escalade, Silverado and Sierra: the converted temperature reaches the 162.1 °C limit in 30 of 50 samples taken every 100 ms, after more than 10 s of propulsion active and with no intake air sensor fault (P0112, P0113) present. It is a Type B code with MIL after two trips. The opposite fault is P0A03. Expect a warning light and possibly reduced electric power.

Likely causes

Signal wire chafed through and shorted to ground
Internal short in the thermistor
Moisture or coolant in the connector bridging signal to ground

Symptoms

  • Check engine or hybrid warning light
  • Displayed electronics temperature extremely high although the system is cool
  • Cooling fans and pump running at full output, drive power limited

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–900
Time0.5–3 h

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

Parts involved

motor electronics coolant temperature sensorhybrid inverterwiring harness

Related codes

P0A00P0A01P0A03P0A04P2BD8

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