P0B28 flags an unstable voltage of hybrid/EV battery B: the reading fluctuates beyond what the battery controller tolerates. Stellantis documents it with P0B28-00 on the Jeep Wrangler 4xe: the MIL is on, and the bulletin warns that after 49 days with this MIL lit the vehicle is no longer allowed to start. The remedy is new software for the battery pack control module, issued first as a rapid service update and later as a regular bulletin; recall 95B must be completed first. The same bulletin lists P0B24 for battery A and codes for voltage variation and cell balancing. Steady low or high voltages of battery B are P0B29 and P0B2A. Besides software, loose busbar or sense contacts can produce the same pattern.
High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.
Symptoms
- MIL on
- Start inhibited after a long period with the MIL lit (Jeep 4xe: 49 days)
- Hybrid/EV system or high-voltage battery warning on
- Warning comes and goes, fault often stored as intermittent
Most likely causes
- Battery pack control module software (Jeep 4xe update)
- Loose busbar, terminal or sense contact in battery B
- Cell with rising internal resistance in battery B
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- It can trigger limp mode.
- It affects emissions.
What each character of P0B28 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- B: Subsystem depends on the code range
- 28: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0B28?
If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.
What causes code P0B28?
The most common causes are: battery pack control module software (Jeep 4xe update); loose busbar, terminal or sense contact in battery B; cell with rising internal resistance in battery B.
Related codes
- P0B27Hybrid/EV Battery B Voltage
- P0B29Hybrid/EV Battery B Voltage Low
- P0B2AHybrid/EV Battery B Voltage High
- P0B24Hybrid/EV Battery A Voltage Unstable
- P0BBEHybrid/EV Battery Pack Voltage Variation
- P0DABHybrid/EV Battery Cell Balancing Performance
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.