Powertrain, generic · Hybrid propulsion

P0B4C Hybrid/EV Battery Voltage Sense D Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Short between channel D sense line and a neighbouring line
Defective input on the cell monitoring module
Corroded tap shared by blocks 4 and 5 (GM two-mode)

Symptoms

  • Hybrid warning message and MIL
  • Electric power and regeneration cut back
  • Engine runs more often than usual

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€50–5,000
Time0.3–6 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

hv battery voltage sense dwiring harnessbms

Related codes

P0B4AP0B4BP0B4DP0B4EP0B47P0B51

References: gsi.ext.gm.com, gsi.ext.gm.com, law.cornell.edu.