Powertrain, generic · Hybrid propulsion

P0B99 Hybrid/EV Battery Voltage Sense S Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0B99 is the erratic variant within the sense S group. A public manufacturer description does not exist. GM's tables cover channel S from the 2011 Volt via the 2012 two-mode trucks and eAssist to the 2019 controllers, yet only with circuit, range, low and high codes (P0B95 to P0B98). CARB 1968.2 obliges manufacturers to monitor battery voltage sensors of a hybrid storage system for circuit and rationality faults and to separate the fault codes by replaceable unit, which is why J2012 reserves this slot. Should a vehicle set it, the technician would look for a sense S connection that works most of the time but breaks briefly, typically a fretting terminal or a cracked solder joint on the board.

Likely causes

Fretting corrosion on the terminal of sense lead S
Cracked solder joint for channel S on the monitoring board
Harness chafing that only shorts under movement

Symptoms

  • Sporadic hybrid warning without a pattern
  • Code often stored as history, hard to reproduce

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€80–5,000
Time1–8 h

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

Parts involved

hv battery voltage sense swiring harnessbms

Related codes

P0B95P0B96P0B97P0B98P0B94P0B9E

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