P0B29 code meaning
Hybrid/EV Battery B Voltage Low
Powertrain system Generic code P0Bxx codes Check engine light
What P0B29 means
P0B29 sets when the voltage of hybrid/EV battery B stays below the range the controller expects for the present state of charge and load. It is the low counterpart to P0B2A; fluctuating readings belong to P0B28 and the general fault to P0B27. No manufacturer publishes a definition of P0B29; Jeep 4xe bulletins confirm the use of a separately monitored battery B only through P0B28. GM handles the analogous whole-pack undervoltage with P0ABC (pack voltage below 24 V). CARB requires battery voltage sensors and cells to be monitored and the fault to be narrowed to the smallest replaceable unit. Weak or deeply discharged cells in that unit are the usual reason, so the controller cuts discharge power and may block driving in EV mode.
P0B29 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 P0B29
- Hybrid/EV system or high-voltage battery warning on
- MIL on
- Battery power limited, less electric drive or assist
- Electric-only driving unavailable
Common causes of P0B29
- Most likelyAged cells with lost capacity in battery B
- PossibleDeep discharge or self-discharge after standstill
- Less likelyVoltage measurement fault in the controller or sense leads
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv battery bBms
What each part of P0B29 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. |
| 29 | The exact fault in that area. |
What to do next
- Note P0B29 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 P0B29
What does P0B29 mean?
P0B29 means "Hybrid/EV Battery B Voltage Low". P0B29 sets when the voltage of hybrid/EV battery B stays below the range the controller expects for the present state of charge and load. It is a generic code, so it means the same on every make.
Is it safe to drive with P0B29?
Drive gently and only to a workshop. With P0B29 the car can go into limp mode (reduced power) to protect itself.
Will P0B29 fail an emissions test?
Yes, it can. P0B29 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 P0B29 to fix?
Difficulty: workshop only. A typical repair takes 1 to 10 hours of work. This is a job for a workshop.
Will P0B29 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.