What Does P0B91 Mean?
The battery management system has detected that the voltage reading from hybrid battery sense circuit "R" is outside the expected range or is not tracking correctly relative to other cell groups. The signal is present but shows abnormal behavior, suggesting cell imbalance, degradation, or a sense circuit resistance issue.
Common Causes
40%
Cell imbalance or degradation within battery module "R" causing voltage deviation
25%
High resistance in the voltage sense circuit due to corroded terminal
20%
Battery management controller calibration drift
15%
Localized thermal issue affecting module "R" voltage behavior
Diagnostic Steps
1
Step 1: Monitor cell group "R" voltage in real time and compare to all other cell groups under varying load conditions.
2
Step 2: Check battery temperature readings near module "R" to rule out thermal-related voltage deviations.
3
Step 3: Perform a battery capacity/balance test using manufacturer-specific diagnostic tools.
4
Step 4: With the HV system de-energized, measure module voltage directly at the terminals with a DVOM and compare to the scan tool reading.
5
Step 5: Inspect cooling pathways near module "R" for blockages or airflow restrictions.
Estimated Repair Cost
$200 - $4,000
Parts + labor, varies by vehicle and location
The battery management system has detected that the voltage reading from hybrid battery sense circuit "R" is outside the expected range or is not tracking correctly relative to other cell groups. The signal is present but shows abnormal behavior, suggesting cell imbalance, degradation, or a sense ci...
The most common cause of P0B91 (Hybrid Battery Voltage Sense "R" Circuit Range/Performance) is: Cell imbalance or degradation within battery module "R" causing voltage deviation
Typical repair costs for P0B91 range from $200 to $4,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Reduced hybrid performance is expected. Continued operation with significant cell imbalance accelerates overall battery degradation. Schedule service soon.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0B91 to identify the root cause.
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Quick Info
Category
Powertrain
System
Hybrid Battery Pack / High-Voltage System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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