Powertrain, generic · Hybrid propulsion

P0BB9 Hybrid/EV Battery Voltage Sense Z Circuit Range/Performance

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

With P0BB9 the controller says that sense Z does not track the pack: the value is within limits, but it stays still or moves the wrong way while the other cells change. GM's 2019 hybrid powertrain control processor 2 enables the comparison once the system voltage is above 10.20 V and the average cell voltage shifts by more than 0.022 V, then demands a trend of at least 0.005 V on Z; 35 failures in 40 samples are Type A. The 2016 Volt variant fails after 7 s within 8 s. In the eAssist mild hybrid, Z has to follow at least half of an average movement above 0.045 V, 20 of 40 samples, Type B. A recalibrated controller or a replaced monitoring board is a more common fix than a new cell.

Likely causes

Z reading static despite changing pack voltage

Monitoring board or controller calibration fault

Cell Z with abnormal charge and discharge behaviour

Symptoms

MIL, driving largely unaffected
Possibly lower assist or regeneration

Repair estimate

DifficultyShop_onlyWorkshop job

Parts and labour€80–5,000

Time0.5–6 h

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

Parts involved

hv battery voltage sense zwiring harnessbms

Related codes

P0BB8 P0BBA P0BBB P0BBC P0BB4 P0ABB

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