P0BACHybrid/EV Battery Voltage Sense W Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- MIL and battery system warning
- Charging and regeneration stopped
- Possible reduced power mode
- Likely causes
- LikelySense lead W in contact with a higher cell potential
- PossibleMonitoring board input for W reading too high
- RareCell W actually overcharged after a balancing fault
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €100 – €6,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.