Powertrain, generic · Hybrid propulsion

P0A99 Hybrid/EV Battery Pack Cooling Fan 2 Control Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0A99 reports a short to ground on the control circuit of the second battery cooling fan. No manufacturer documents this exact code publicly; Ford's two-fan Escape/Mariner Hybrid packs show that a second fan exists (there with P0A96). CARB requires the outputs used for battery thermal management to be monitored for circuit faults. The fan 1 counterpart P0A84 shows the usual GM logic: with the fan commanded at low duty, an output voltage below about 0.26 V in 16 of 20 samples sets a Type B code. The same approach is to be expected for fan 2. With the output held low the fan may not respond, cooling capacity falls and power may be limited. Open and high faults are P0A96 and P0A9A.

Likely causes

Fan 2 control wire shorted to ground
Internal short in fan 2 control input
Moisture or corrosion in the fan 2 connector

Symptoms

  • Check engine or hybrid warning
  • Fan 2 does not run when commanded
  • Reduced hybrid power in hot conditions

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

P0A96P0A9AP0A84P0A97

References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov.