Powertrain, generic · Hybrid propulsion

P0B9D Hybrid/EV Battery Voltage Sense T Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

If sense T reports more voltage than its cell can hold, the battery controller stores P0B9D. GM documents it on several systems. The 2019 battery energy control module and the 2016 Volt set it at 4.8 V or above for 1.4 s within 2 s, Type A, and only when no open sense line fault is pending. The 16OBDG02 programme with a dedicated battery sensor module uses 4.90 V in 14 of 18 samples. The eAssist mild hybrid sets it above 4.65 V in 7 of 10 samples, Type B. In the 2012 two-mode trucks the channel is block 20, the final NiMH block, with a limit of 23 V and 15 of 20 samples, Type B. Most such readings come from wiring touching a higher potential or a faulty measuring input.

Likely causes

Sense lead T shorted to a higher cell or busbar
Measuring input for channel T drifting high
Cell or block T genuinely overcharged

Symptoms

  • MIL and service hybrid or EV system message
  • Charging power reduced

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 twiring harnessbms

Related codes

P0B9AP0B9BP0B9CP0B9EP0B98P0BA2

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