What it means
The control module monitors voltage in hybrid/EV battery A and sets this code when the measured voltage falls below the expected range. The code identifies a low-voltage condition; it does not by itself establish whether the battery or its sensing circuit caused it.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Hybrid/EV battery A is a monitored high-voltage battery section or assembly, and the battery control system measures its voltage through a sensing circuit. P0B25 sets when the reported voltage for battery A falls below the allowed range; the code alone cannot tell whether the section is depleted or the reading is being pulled low by a circuit fault.
Common causes
Most likely first.
- Battery A voltage below expected range
- Voltage measurement circuit fault
- Loose or poor electrical connection
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Save freeze-frame data and compare battery A's live voltage with other battery sections, noting whether the low reading occurs at rest, under load, or while charging.
- Check for related battery, charging, or isolation codes that may help explain the low battery A reading.
- With the high-voltage system made safe using the manufacturer's procedure, inspect battery A connectors, terminals, and sensing wires for looseness, corrosion, or damage.
- Check whether battery A's reported voltage recovers during charging or changes abnormally under load, and compare its behavior with other sections.
- Test the battery A voltage-sensing circuit and section condition to the manufacturer's specifications before deciding which component needs service.
Common fixes
- Repair a loose or corroded battery A connection.
- Repair damaged wiring or a fault in battery A's voltage-measurement circuit.
- Service or replace battery A if testing confirms the section itself is below the expected voltage.
Can I keep driving?
Limit driving, especially long trips and hard acceleration, because the vehicle may reduce propulsion or lose charging capability. If the vehicle enters limp mode or the hybrid system warning is severe, stop safely and arrange service.
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.