Powertrain, generic · Hybrid propulsion

P0B73 Hybrid/EV Battery Voltage Sense L Circuit Range/Performance

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

Channel L delivers a value, but P0B73 tells you that the value is not credible. GM checks this in three ways. The 2016 Chevrolet Volt and the 2019 lithium-ion systems test whether cell L moves in the same direction as the average once that average changes by more than 0.022 V, failing 7 of 8 seconds or 35 of 40 samples respectively, Type A. The BAS Plus mild hybrid demands at least half of the average movement, 20 of 40 samples, Type B. The 2012 two-mode trucks treat L as nickel-metal hydride block 12 and compare blocks 12 and 13, scaled by twenty, with the pack voltage, failing beyond 70 V in 160 of 170 samples, Type B. A battery controller reflash or measuring board repair is the usual remedy.

Likely causes

Channel L input not following real cell voltage changes

Battery controller software or calibration issue

Corroded cell tap slowing the signal

Symptoms

MIL with normal driving behaviour
Reduced electric range or assist

Repair estimate

DifficultyShop_onlyWorkshop job

Parts and labour€50–5,000

Time0.3–8 h

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

Parts involved

hv battery voltage sense lwiring harnessbms

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