Powertrain, generic · Hybrid propulsion

P0AAA Hybrid/EV Battery Voltage Isolation Sensor Circuit High

Check engine lightOn
EmissionsNot relevant
Drive cycleRequired
Limp modeNo

P0AAA is the high-side counterpart of P0AA9: the isolation sensor reports a rail-to-ground voltage above anything the pack can produce. GM's tables tie the limit to the pack: over 333 V in the 2016 table and over 416 V in the 2019 table, each in 320 of 400 samples with the bias switch open, Type B, two trips. The 2013 GM table instead flags a mid-pack reading that differs from the motor controller's voltage by more than 15 V. Likely sources are an open reference or ground in the measuring circuit or a failed input stage in the battery controller. No public bulletin from another maker names this code. The car usually stays drivable with warnings, but isolation monitoring is lost, and P0AA6 cannot be trusted until it is fixed.

Likely causes

Open ground or reference in the isolation measuring circuit
Failed isolation input stage in the battery controller
Sense lead shorted to another HV potential inside the pack

Symptoms

  • Check engine and hybrid or EV warning lights
  • Isolation monitoring disabled while the code is active

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–2,500
Time0.5–4 h

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

Parts involved

hv battery voltage isolation sensorwiring harnessbms

Related codes

P0AA9P0AA8P0AA7P0AABP0AA6

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com.