P0BB9Hybrid/EV Battery Voltage Sense Z Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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.
- What you may notice
- MIL, driving largely unaffected
- Possibly lower assist or regeneration
- Likely causes
- LikelyZ reading static despite changing pack voltage
- PossibleMonitoring board or controller calibration fault
- RareCell Z with abnormal charge and discharge behaviour
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €80 – €5,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.