P0B8B code meaning
Hybrid/EV Battery Voltage Sense Q Circuit
Powertrain system Generic code P0Bxx codes Check engine light
What P0B8B means
P0B8B marks an open circuit on voltage sense Q, the seventeenth channel. In GM's BAS Plus mild hybrid tables Q is the first channel whose open test is blocked by code P1B37 instead of P1B36, which suggests it sits in the next measuring group of the battery interface module; the criterion stays lines N and N-1 below 1.4 V with a change above 0.5 V in 200 ms, 7 of 10 samples, Type B. GM's 2019 battery controller uses 0.8 s in a 1.6 s window, the 2016 version 0.6 s, both Type A with the 1.3 V and 36 mV criteria. The 2011 Volt list includes P0B8B as well. The two-mode NiMH trucks have no circuit code for block 17. Ford does not list it. Typically the vehicle restricts or blocks electric operation until repaired.
P0B8B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 10 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0B8B
- MIL and service vehicle message
- Electric operation blocked or limited
- Fuel consumption rises on hybrids
Common causes of P0B8B
- Most likelySense lead Q open between cell tap and module
- PossibleLoose or corroded connector at the second measuring group
- Less likelyFault in the battery interface module
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 P0B8B 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. |
| 8B | The exact fault in that area. |
What to do next
- Note P0B8B 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 P0B8B
What does P0B8B mean?
P0B8B means "Hybrid/EV Battery Voltage Sense Q Circuit". P0B8B marks an open circuit on voltage sense Q, the seventeenth channel. It is a generic code, so it means the same on every make.
Is it safe to drive with P0B8B?
Drive gently and only to a workshop. With P0B8B the car can go into limp mode (reduced power) to protect itself.
Will P0B8B fail an emissions test?
Yes, it can. P0B8B 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 P0B8B to fix?
Difficulty: workshop only. A typical repair takes 1 to 10 hours of work. This is a job for a workshop.
Will P0B8B clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.