P0B42 code meaning
Hybrid/EV Battery Voltage Sense B Circuit Low
Powertrain system Generic code P0Bxx codes Check engine light
What P0B42 means
P0B42 sets when cell voltage channel B reads implausibly low, below what any usable cell would show. GM's battery energy control module sets it at 0.2 V or less for 1.4 s within a 2 s window, Type A, one trip, and only when no open sense line, slave communication or balancing fault is present. FCA uses P0B42 as Voltage Sense 2 Circuit Low on the 2022 Grand Wagoneer and Wagoneer with the 5.7 L eTorque mild hybrid; its bulletin calls the MIL false, mentions inoperative start-stop and a car that seems to run on fuel only, and prescribes a battery pack control module update. Cells that are actually weak set separate cell voltage codes. High and range faults are P0B43 and P0B41.
P0B42 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor0.2 to 6 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0B42
- MIL on
- Start-stop inoperative
- Vehicle behaves as if running on the engine only
Common causes of P0B42
- Most likelyBattery pack control module software causing a false MIL (FCA eTorque)
- PossibleSense line shorted to the adjacent line or to the cell negative
- Less likelyMeasurement input of the cell monitoring chip 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 bWiring harnessBms
What each part of P0B42 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. |
| 42 | The exact fault in that area. |
What to do next
- Note P0B42 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 P0B42
What does P0B42 mean?
P0B42 means "Hybrid/EV Battery Voltage Sense B Circuit Low". P0B42 sets when cell voltage channel B reads implausibly low, below what any usable cell would show. It is a generic code, so it means the same on every make.
Is it safe to drive with P0B42?
Drive gently and only to a workshop. With P0B42 the car can go into limp mode (reduced power) to protect itself.
Will P0B42 fail an emissions test?
Yes, it can. P0B42 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 P0B42 to fix?
Difficulty: workshop only. A typical repair takes 0.2 to 6 hours of work. This is a job for a workshop.
Will P0B42 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.