P0AF8 code meaning
Hybrid/EV Battery System Voltage
Powertrain system Generic code P0Axx codes Check engine light
What P0AF8 means
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.
P0AF8 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0AF8
- MIL and hybrid or EV warning on
- Battery saver or low battery message
- Intermittent no crank or reduced hybrid power
Common causes of P0AF8
- Most likelyLoose or arcing high-voltage battery cable connection
- PossiblePack or bus voltage sensing circuit inaccurate
- PossibleLow 12 V supply or loose 12 V power fuse affecting the measuring modules
- Less likelyHigh resistance in a pack fuse or main contactor
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv batteryBms
What each part of P0AF8 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| A | Area: hybrid propulsion. |
| F8 | The exact fault in that area. |
What to do next
- Note P0AF8 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0AF8
What does P0AF8 mean?
P0AF8 means "Hybrid/EV Battery System Voltage". P0AF8 compares the battery pack voltage reported by the battery controller with an independent measurement on the high-voltage bus. It is a generic code, so it means the same on every make.
Is it safe to drive with P0AF8?
Drive gently and only to a workshop. With P0AF8 the car can go into limp mode (reduced power) to protect itself.
Will P0AF8 fail an emissions test?
Yes, it can. P0AF8 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0AF8 to fix?
Difficulty: workshop only. A typical repair takes 1 to 6 hours of work. This is a job for a workshop.
Will P0AF8 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.