What it means
The supply voltage to battery charger B control module is high. Charger may not start or operate reliably.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Battery charger B's control electronics receive power through a low-voltage supply circuit. P2E31 sets when the monitored supply rises above its acceptable range, such as from a short to battery positive or an overvoltage condition, and charger B may shut down to protect itself.
Common causes
Most likely first.
- Alternator overvoltage
- Wire shorted to B+
Symptoms
- Charge status indicator shows fault
- Charging may not start or interrupts
- Slower-than-expected charge rate
How to diagnose it
- Read freeze-frame and live data for charger B supply voltage to establish whether the high reading is current and whether it coincides with vehicle charging or operation.
- Inspect the charger B supply harness and connectors for insulation damage or a wire contacting battery positive.
- Check the vehicle's charging-system voltage and related data against the manufacturer's specification to see whether a broader overvoltage condition is present.
- Test the charger B supply circuit for an unwanted connection to B+ using the manufacturer's procedure.
- If supply wiring and vehicle charging voltage are correct, use the manufacturer's diagnostic procedure to check the charger B module input.
Common fixes
- Repair a supply wire shorted to battery positive.
- Repair damaged or poorly seated charger B connector terminals.
- Correct an alternator or vehicle charging-system overvoltage condition if confirmed.
- Replace the charger B module only if its input circuit tests point to an internal fault.
Can I keep driving?
Charging may be interrupted or unavailable, and an overvoltage fault can affect other electrical systems. Avoid repeated charging attempts and have the vehicle checked promptly, especially if other electrical warnings appear.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.