P0B84 code meaning
Hybrid/EV Battery Voltage Sense O Circuit High
Powertrain system Generic code P0Bxx codes Check engine light
What P0B84 means
P0B84 is stored when channel O sits above the upper limit of a credible cell voltage. For GM lithium-ion packs that limit is 4.8 V, held 1.4 s in a 2 s window, Type A; the 2016 program with a separate sense module tolerates up to 4.90 V and counts 14 failures in 18 samples, also Type A. GM's BAS Plus mild hybrid uses a lower ceiling of 4.65 V and a Type B rating. On the 2012 two-mode hybrids the reading belongs to NiMH block 15, which must exceed 23 V in 15 of 20 samples. For the driver the effect is a warning and a battery that is no longer charged fully or used for electric drive. Since true overvoltage is rare, the measuring lead and the input of the monitoring electronics are checked first.
P0B84 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 P0B84
- MIL and battery warning
- Charging ends early
- Less electric assist
Common causes of P0B84
- Most likelySense lead O shorted to a higher cell tap
- PossibleMonitoring input of channel O reading too high
- Less likelyCell overcharged because balancing failed
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 oWiring harnessBms
What each part of P0B84 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. |
| 84 | The exact fault in that area. |
What to do next
- Note P0B84 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 P0B84
What does P0B84 mean?
P0B84 means "Hybrid/EV Battery Voltage Sense O Circuit High". P0B84 is stored when channel O sits above the upper limit of a credible cell voltage. It is a generic code, so it means the same on every make.
Is it safe to drive with P0B84?
Drive gently and only to a workshop. With P0B84 the car can go into limp mode (reduced power) to protect itself.
Will P0B84 fail an emissions test?
Yes, it can. P0B84 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 P0B84 to fix?
Difficulty: workshop only. A typical repair takes 1 to 8 hours of work. This is a job for a workshop.
Will P0B84 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.