Powertrain, generic · Hybrid propulsion

P0B20 Hybrid/EV Battery Pack Voltage Sense D Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0B20 sets when pack voltage measurement D falls below its plausible minimum. The cause is usually electrical: a sense lead shorted to ground, an interrupted fuse or resistor in the measurement path, or a damaged controller input. No manufacturer documents P0B20 publicly. GM shows the analogous check on channel A, where its BECM sets P0ABC once pack-side voltage stays under 24 V for 1.6 s within 2 s, Type A, one trip. CARB requires out-of-range monitoring of battery voltage sensors in hybrid storage systems. The high counterpart is P0B21, plausibility faults are P0B1F. An implausibly low reading can block precharge, so the vehicle may not become ready.

Likely causes

Sense lead of channel D shorted to ground
Fuse or resistor in the sense path open
Measurement input of the battery controller defective

Symptoms

  • Vehicle may not reach Ready or may shut down the high-voltage system
  • MIL and hybrid/EV system warning on
  • Battery power limited, reduced electric drive or assist

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–2,500
Time1–6 h

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

Parts involved

hv battery pack voltage sense dwiring harnessbms

Related codes

P0B1EP0B1FP0B21P0B22P0B1BP0ABC

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