What Does P0B55 Mean?
P0B55 indicates that the hybrid battery voltage sense circuit for cell group "F" is reporting values outside the expected range or exhibiting poor performance characteristics. The BMS is receiving voltage readings that are plausible but do not match the expected behavior relative to other cell groups or operating conditions. This often points to a degrading cell group or a sensing circuit with increased resistance.
Common Causes
30%
Cell group F degradation causing voltage to drift outside normal range relative to other groups
25%
High resistance in the voltage sense wiring or connector for cell group F
20%
Cell balancing failure allowing group F to diverge from other cell groups
15%
Temperature-related voltage variation due to cooling system imbalance affecting group F
10%
BMS calibration drift or software error in group F voltage thresholds
Diagnostic Steps
1
Use the BMS diagnostic data to compare cell group F voltage against all other cell groups at rest and under load.
2
Check the hybrid battery cooling system for blockages or uneven airflow near cell group F.
3
Measure actual cell group F voltage at the module terminals and compare with the BMS-reported value to isolate sensing vs. cell issues.
4
Inspect the voltage sense wiring for increased resistance due to corrosion or damage.
5
Perform a battery capacity test to evaluate cell group F health relative to the rest of the pack.
6
Check for any pending BMS software updates or calibration resets from the manufacturer.
Estimated Repair Cost
$200 - $4,000
Parts + labor, varies by vehicle and location
P0B55 indicates that the hybrid battery voltage sense circuit for cell group "F" is reporting values outside the expected range or exhibiting poor performance characteristics. The BMS is receiving voltage readings that are plausible but do not match the expected behavior relative to other cell group...
The most common cause of P0B55 (Hybrid Battery Voltage Sense "F" Circuit Range/Performance) is: Cell group F degradation causing voltage to drift outside normal range relative to other groups
Typical repair costs for P0B55 range from $200 to $4,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A cell group operating outside its expected range may indicate early-stage cell degradation that could progress to more serious conditions if unaddressed. The vehicle may experience reduced electric range and performance. Continued driving is generally safe in the short term if no other battery warnings are present.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0B55 to identify the root cause.
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Quick Info
Category
Powertrain
System
Hybrid Battery / High-Voltage System
Difficulty
Type
Generic (SAE)
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