What Does P0B45 Mean?
DTC P0B45 is a general circuit fault code for the hybrid battery voltage sense "C" circuit at the individual battery module level (as opposed to the pack-level P0B19). The BMS has detected an electrical malfunction in the sense line monitoring a specific "C" battery module's voltage. This generic code typically indicates an open circuit or complete loss of signal from the module-level voltage sensor.
Safety Warning
Loss of individual module voltage monitoring creates a blind spot in the BMS safety system. The affected module cannot be monitored for dangerous overvoltage or undervoltage conditions, posing a risk of undetected thermal events.
Common Causes
30%
Open circuit in the "C" battery module voltage sense wiring
25%
Disconnected or damaged connector at the "C" battery module tap point
20%
Failed cell monitoring IC or voltage sense circuit on the "C" module
15%
BMS cell supervision board fault affecting the "C" input
10%
Corroded battery module terminal affecting the sense connection
Diagnostic Steps
1
Retrieve freeze frame data and identify which specific battery module the "C" designation refers to in the vehicle's service documentation.
2
Verify continuity of the "C" module voltage sense wiring from the cell tap to the cell supervision circuit.
3
Inspect the "C" module connector and cell tap terminals for corrosion, heat damage, or physical damage.
4
Using the scan tool, check if the "C" module voltage reads zero, maximum, or an implausible fixed value.
5
If wiring is intact, check the cell monitoring IC or supervision board for the "C" module channel.
6
Measure actual cell/module voltage at the terminals with appropriate equipment and compare to expected values.
Estimated Repair Cost
$250 - $3,000
Parts + labor, varies by vehicle and location
DTC P0B45 is a general circuit fault code for the hybrid battery voltage sense "C" circuit at the individual battery module level (as opposed to the pack-level P0B19). The BMS has detected an electrical malfunction in the sense line monitoring a specific "C" battery module's voltage. This generic co...
The most common cause of P0B45 (Hybrid Battery Voltage Sense "C" Circuit) is: Open circuit in the "C" battery module voltage sense wiring
Typical repair costs for P0B45 range from $250 to $3,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Loss of individual module voltage monitoring creates a blind spot in the BMS safety system. The affected module cannot be monitored for dangerous overvoltage or undervoltage conditions, posing a risk of undetected thermal events.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0B45 to identify the root cause.
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Quick Info
Category
Powertrain
System
Hybrid/EV Battery System
Difficulty
Type
Generic (SAE)
Recommended Tools
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