P0B66Hybrid/EV Battery Voltage Sense I 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
- When channel I claims a voltage above what its cell or block can physically reach, the controller stores P0B66. The thresholds GM publishes depend on chemistry and architecture: lithium-ion packs with a battery energy control module set it at 4.8 V or more for 1.4 s in a 2 s window, Type A, one trip; the BAS Plus mild hybrid at above 4.65 V in 7 of 10 samples, Type B; the 2012 two-mode trucks, which measure nickel-metal hydride block 9 rather than single cells, above 23 V in 15 of 20 samples, Type B. Every limit sits clearly above normal full charge, so a real overcharged cell is unlikely. Look first for a sense lead touching the next tap up or for a measuring input that has lost its reference.
- What you may notice
- Charging stops or is refused
- MIL and reduced power
- Likely causes
- LikelyChannel I lead touching a higher-potential tap
- PossibleOpen reference or ground of the measuring chip
- RareGenuinely overcharged cell after a charging control 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.