Powertrain, generic · Hybrid propulsion

P0B9F Hybrid/EV Battery Voltage Sense U Circuit

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

P0B9F covers an open or high-resistance sense U lead, channel twenty-one. From U onward the 2012 two-mode trucks drop out, as their pack has only twenty blocks, so this code is a lithium-ion matter at GM. In the eAssist mild hybrid the test is the familiar one, lines N and N-1 both under 1.4 V with a change above 0.5 V within 200 ms in 7 of 10 samples, Type B, but it is now blocked by P1B38 instead of P1B37. The 16OBDG02 programme measures the sense line resistance and sets above 30.00 in 7 of 9 samples, Type A. The 2016 Volt and ELR decide in 0.6 s, the 2019 controller in 0.8 s of 1.6 s, both on adjacent-cell differences of 1.3 V and splice checks.

Likely causes

Sense lead U interrupted or detached from its cell

Corroded terminal raising the resistance of lead U

Fault in the balancing circuit used for the channel U test

Symptoms

MIL and hybrid or EV system warning
No start or ready mode on some vehicles
Charging not possible

Repair estimate

DifficultyShop_onlyWorkshop job

Parts and labour€150–6,500

Time1–10 h

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

Parts involved

hv battery voltage sense uwiring harnessbms

Related codes

P0BA0 P0BA1 P0BA2 P0BA3 P0B9A P0BA4

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