Powertrain, generic · Hybrid propulsion

P0B74 Hybrid/EV Battery Voltage Sense L Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0B74 is set when channel L reads implausibly low. On the 2012 GM two-mode hybrids, where L is nickel-metal hydride block 12 of 20, the battery pack control module needs both block 12 and block 13 under 2 V in 15 of 20 samples before it stores the code as Type B; no battery control module fault P0A1F may be active. For lithium-ion packs GM's 2016 and 2019 tables use 0.2 V or less for 1.4 s within 2 s, Type A, and the BAS Plus mild hybrid 1.4 V in 7 of 10 samples, Type B. A short of the sense lead to a lower potential, a defective monitoring input or, more rarely, a cell that has really collapsed are the candidates. The vehicle will normally restrict electric operation.

Likely causes

Channel L sense lead shorted to a lower potential
Defective measuring input in the battery controller
Cell or block on channel L actually failed

Symptoms

  • MIL and hybrid system warning
  • Electric operation restricted
  • Engine runs continuously on hybrids

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–6,000
Time1–8 h

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

Parts involved

hv battery voltage sense lwiring harnessbms

Related codes

P0B72P0B73P0B75P0B76P0B6FP0B79

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com.