What Does P0B25 Mean?
The battery management system has detected that hybrid battery module "A" voltage has dropped below the minimum acceptable threshold. Low module voltage indicates either severely depleted cells, a cell group failure within the module, or high-resistance connections causing excessive voltage drop. This condition reduces the available hybrid power and can cause cell damage from over-discharge.
Safety Warning
Do not drive the vehicle. Low module voltage indicates cell failure, which can lead to over-discharge damage, internal short circuits, and potential thermal events. The vehicle may lose hybrid assist unexpectedly.
Common Causes
40%
One or more failed cells within battery module A with reduced capacity causing low voltage under load
25%
High-resistance bus bar connection or internal cell tab causing excessive voltage drop
20%
Cell imbalance within module A where one cell is significantly weaker, dragging down overall module voltage
15%
BMS cell balancing failure allowing module A cells to become deeply discharged relative to the rest of the pack
Diagnostic Steps
1
Step 1: Record module A voltage and compare to all other modules via scan tool battery data. A difference of more than 1V from the pack average strongly indicates a module-level failure.
2
Step 2: Fully charge the battery pack and then measure module A voltage at rest. If it remains significantly lower than peers after a full charge, the module has reduced capacity.
3
Step 3: Measure individual cell voltages within module A using an HV-rated DVOM. Identify any cell reading below 3.0V (for lithium cells) or below the manufacturer's minimum threshold.
4
Step 4: Check bus bar connections at module A for high resistance using a milliohm meter. Connections should be less than 1 milliohm; higher values indicate a resistive joint.
5
Step 5: If a single weak cell is identified, the module may require replacement. Verify the replacement module is within 0.1V of the pack average before installation.
Estimated Repair Cost
$500 - $5,000
Parts + labor, varies by vehicle and location
The battery management system has detected that hybrid battery module "A" voltage has dropped below the minimum acceptable threshold. Low module voltage indicates either severely depleted cells, a cell group failure within the module, or high-resistance connections causing excessive voltage drop. Th...
The most common cause of P0B25 (Hybrid Battery "A" Voltage Low) is: One or more failed cells within battery module A with reduced capacity causing low voltage under load
Typical repair costs for P0B25 range from $500 to $5,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Do not drive the vehicle. Low module voltage indicates cell failure, which can lead to over-discharge damage, internal short circuits, and potential thermal events. The vehicle may lose hybrid assist unexpectedly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0B25 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Hybrid Battery / High Voltage System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
