P0BAC code meaning
Hybrid/EV Battery Voltage Sense W Circuit High
Powertrain system Generic code P0Bxx codes Check engine light
What P0BAC means
P0BAC is the upper counterpart to P0BAB: channel W reports more voltage than a single cell can plausibly hold. GM sets the limit at 4.8 V or more for 1.4 s within 2 s in the 2011 and 2016 Volt battery modules, which makes it a one-trip fault. The 16OBDG02 programme fails at above 4.90 V in 14 of 18 samples, Type A, while the eAssist battery is stricter with more than 4.65 V in seven of ten samples, Type B. A high reading usually comes from a lead touching the potential of the next cell up or from a faulty input, less often from a genuinely overcharged cell. Because overcharging is a safety risk, the controller typically cuts charging and regeneration until the cause is found.
P0BAC at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 8 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0BAC
- MIL and battery system warning
- Charging and regeneration stopped
- Possible reduced power mode
Common causes of P0BAC
- Most likelySense lead W in contact with a higher cell potential
- PossibleMonitoring board input for W reading too high
- Less likelyCell W actually overcharged after a balancing fault
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv battery voltage sense wWiring harnessBms
What each part of P0BAC means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| B | Area: hybrid propulsion. |
| AC | The exact fault in that area. |
What to do next
- Note P0BAC 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 P0BAC
What does P0BAC mean?
P0BAC means "Hybrid/EV Battery Voltage Sense W Circuit High". P0BAC is the upper counterpart to P0BAB: channel W reports more voltage than a single cell can plausibly hold. It is a generic code, so it means the same on every make.
Is it safe to drive with P0BAC?
Drive gently and only to a workshop. With P0BAC the car can go into limp mode (reduced power) to protect itself.
Will P0BAC fail an emissions test?
Yes, it can. P0BAC 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 P0BAC to fix?
Difficulty: workshop only. A typical repair takes 1 to 8 hours of work. This is a job for a workshop.
Will P0BAC clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.