P0B8D code meaning
Hybrid/EV Battery Voltage Sense Q Circuit Low
Powertrain system Generic code P0Bxx codes Check engine light
What P0B8D means
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.
P0B8D at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 8 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0B8D
- MIL and reduced power mode
- Engine runs more often on hybrids
Common causes of P0B8D
- Most likelyShort in the Q sense path to a lower potential
- PossibleSense module input reading low
- Less likelyCell or block 17 deeply discharged
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv battery voltage sense qWiring harnessBms
What each part of P0B8D means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| B | Area: hybrid propulsion. |
| 8D | The exact fault in that area. |
What to do next
- Note P0B8D and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0B8D
What does P0B8D mean?
P0B8D means "Hybrid/EV Battery Voltage Sense Q Circuit Low". P0B8D reports a voltage on sense Q below the lowest credible cell value. It is a generic code, so it means the same on every make.
Is it safe to drive with P0B8D?
Drive gently and only to a workshop. With P0B8D the car can go into limp mode (reduced power) to protect itself.
Will P0B8D fail an emissions test?
Yes, it can. P0B8D is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0B8D to fix?
Difficulty: workshop only. A typical repair takes 1 to 8 hours of work. This is a job for a workshop.
Will P0B8D clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.