Powertrain, generic · Hybrid propulsion

P0A9A Hybrid/EV Battery Pack Cooling Fan 2 Control Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0A9A reports a short to voltage on the control circuit of the second battery cooling fan. No manufacturer publishes this exact code; CARB requires the electronic outputs of battery thermal management to be checked for circuit faults. The fan 1 counterpart P0A85 shows the usual method: GM samples the output while the fan is commanded between 11 % and 100 % duty and counts a voltage above 9 V as a failure, setting a Type B code after 16 of 20 samples. A fan 2 diagnosis would work the same way. Depending on the circuit design the fan runs constantly or stops responding; a constantly running fan can drain the 12 V battery. Open and low faults are P0A96 and P0A99; a mechanically stuck-on fan is P0A98.

Likely causes

Fan 2 control wire shorted to supply voltage
Fan 2 control input internally open or shorted to supply
Corroded connector with leakage to supply

Symptoms

  • Check engine or hybrid warning
  • Fan 2 runs constantly or not at all
  • Possible 12 V battery drain when parked

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–700
Time0.5–3 h

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

Parts involved

hybrid battery cooling fan 2wiring harnessbms

Related codes

P0A96P0A99P0A85P0A98

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