Powertrain, generic · Hybrid propulsion

P0DAA Battery Charging System Isolation Fault

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P0DAA reports that the resistance between the charging-side HV bus and chassis ground has fallen too low, so the charging path or the battery is no longer safely insulated. GM documents the logic for the 2014 Chevrolet Volt and Cadillac ELR in the HPC2 (VICM): in charge-only mode the active isolation resistance is measured, at most once per wake-up; below 325 kOhm, or 400 kOhm while the code is active, for 10 s, and with five of the last ten results low, the code sets as Type A with MIL after one trip. GM preliminary information PIC5920 links it to vehicles that will not charge and points to coolant leaking into the battery pack or insulation loss in the cells; technicians check the pack drain plug and reprogram HPCM2 and BECM, and call support if isolation stays under 275 kOhm. GM used P0AA6 for this on 2011–13 Volts.

Likely causes

Coolant leaking into the battery pack (GM)
Insulation loss within battery cells or sections (GM)
Outdated HPCM2/BECM calibration (GM, 2011–2014)
Damaged insulation in the on-board charger or charging cables

Symptoms

  • Vehicle will not charge
  • MIL on (GM Type A)
  • Low coolant level in the battery coolant reservoir

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–6,000
Time1–10 h

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

Parts involved

on board chargerisolation monitorhv battery pack

Related codes

P0AA6

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