Powertrain, generic · Hybrid propulsion

P0AF8 Hybrid/EV Battery System Voltage

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0AF8 compares the battery pack voltage reported by the battery controller with an independent measurement on the high-voltage bus. GM calls it system voltage correlation: with the contactors closed, the 2019 tables fail it when the pack reading differs from the inverter bus voltage by more than 13.95 V, or from the charger bus voltage by more than 14.95 V, 400 of 500 samples at 25 ms, Type A. The 2011 Volt table uses 12 V and Type A, the 2013 eAssist table 5.77 V against the motor controller, Type B. GM's Saturn Vue Hybrid PIP4005A links P0AF8 with P0AFB to a loose negative battery cable, and Volt PIC6089B mentions it with low 12 V system faults. P0AFA and P0AFB judge the voltage level itself.

Likely causes

Loose or arcing high-voltage battery cable connection
Pack or bus voltage sensing circuit inaccurate
Low 12 V supply or loose 12 V power fuse affecting the measuring modules
High resistance in a pack fuse or main contactor

Symptoms

  • MIL and hybrid or EV warning on
  • Battery saver or low battery message
  • Intermittent no crank or reduced hybrid power

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–3,000
Time1–6 h

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

Parts involved

hv batterybms

Related codes

P0AFAP0AFBP0AF9P0ABBP0ABCP0ABD

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.