P0B8DHybrid/EV Battery Voltage Sense Q Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P0B8D reports a voltage on sense Q below the lowest credible cell value. GM's lithium-ion battery controllers in the 2016 and 2019 tables use 0.2 V or less for 1.4 s within 2 s, Type A, and the 2016 program with a separate sense module 0.20 V with 14 of 18 samples. GM's BAS Plus mild hybrid applies 1.4 V, 7 of 10 samples, Type B. In the 2012 two-mode NiMH pack Q is block 17 and the battery pack control module requires blocks 17 and 18 both under 2 V for 15 of 20 samples. The low test is suppressed while an open-line fault is active, so P0B8B takes precedence for a broken lead. Shorts in the sense path are the leading cause; a real deep discharge of the cell would normally trigger further battery codes too.
- What you may notice
- MIL and reduced power mode
- Engine runs more often on hybrids
- Likely causes
- LikelyShort in the Q sense path to a lower potential
- PossibleSense module input reading low
- RareCell or block 17 deeply discharged
- 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: €100 – €6,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.