P0B99 code meaning
Hybrid/EV Battery Voltage Sense S Circuit Intermittent/Erratic
Powertrain system Generic code P0Bxx codes Check engine light
What P0B99 means
P0B99 is the erratic variant within the sense S group. A public manufacturer description does not exist. GM's tables cover channel S from the 2011 Volt via the 2012 two-mode trucks and eAssist to the 2019 controllers, yet only with circuit, range, low and high codes (P0B95 to P0B98). CARB 1968.2 obliges manufacturers to monitor battery voltage sensors of a hybrid storage system for circuit and rationality faults and to separate the fault codes by replaceable unit, which is why J2012 reserves this slot. Should a vehicle set it, the technician would look for a sense S connection that works most of the time but breaks briefly, typically a fretting terminal or a cracked solder joint on the board.
P0B99 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 P0B99
- Sporadic hybrid warning without a pattern
- Code often stored as history, hard to reproduce
Common causes of P0B99
- Most likelyFretting corrosion on the terminal of sense lead S
- PossibleCracked solder joint for channel S on the monitoring board
- Less likelyHarness chafing that only shorts under movement
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 sWiring harnessBms
What each part of P0B99 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. |
| 99 | The exact fault in that area. |
What to do next
- Note P0B99 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 P0B99
What does P0B99 mean?
P0B99 means "Hybrid/EV Battery Voltage Sense S Circuit Intermittent/Erratic". P0B99 is the erratic variant within the sense S group. It is a generic code, so it means the same on every make.
Is it safe to drive with P0B99?
Drive gently and only to a workshop. With P0B99 the car can go into limp mode (reduced power) to protect itself.
Will P0B99 fail an emissions test?
Yes, it can. P0B99 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 P0B99 to fix?
Difficulty: workshop only. A typical repair takes 1 to 8 hours of work. This is a job for a workshop.
Will P0B99 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.