P0B4CHybrid/EV Battery Voltage Sense D Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- From the driver's seat P0B4C looks like a battery problem: the hybrid warning comes on and electric power is cut back. Technically it is a measuring fault on cell channel D, whose reading has fallen below what even a deeply discharged cell would show. GM's battery energy control module uses 0.2 V or less, held for 1.4 s within 2 s, Type A, and skips the test while open sense line or communication faults are active. On the 2012 two-mode full-size hybrids, channel D is block 4, and the code needs blocks 4 and 5 both below 2 V in 15 of 20 samples, Type B. A genuinely weak cell produces separate cell voltage codes, so P0B4C points to wiring or the monitoring module.
- What you may notice
- Hybrid warning message and MIL
- Electric power and regeneration cut back
- Engine runs more often than usual
- Likely causes
- LikelyShort between channel D sense line and a neighbouring line
- PossibleDefective input on the cell monitoring module
- RareCorroded tap shared by blocks 4 and 5 (GM two-mode)
- 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: €50 – €5,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.