Powertrain, generic · Hybrid propulsion

P0A06 Motor Electronics Coolant Pump A Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The control line of pump A in the drive electronics coolant loop sits at a voltage below what the module expects for the commanded state, usually because the line or the pump input is shorted to ground. Depending on the driver design, the pump then runs uncontrolled or not at all. No manufacturer documents P0A06 publicly; GM's Volt reports a short of the comparable pump control line under P0CE9 (16 of 20 samples at 250 ms, Type B). CARB requires circuit checks of inverter cooling outputs, and Toyota patents show why a failed pump must be separated from radiator or fan faults. P0A05 is the open case, P0A07 the short to voltage. A failing pump soon leads to power reduction.

Likely causes

Control wire chafed against the body and shorted to ground
Internal short at the pump's control input
Water or coolant in the pump connector

Symptoms

  • Hybrid system or check engine light
  • Electronics temperature rising quickly, power limited
  • Pump silent when commanded on, or running continuously

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–800
Time0.5–3 h

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

Parts involved

motor electronics coolant pump awiring harnesshybrid control module

Related codes

P0A05P0A07P0B39P0E4FP0A93P0CEB

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