What it means
A control module has stopped receiving expected network messages from hybrid/EV battery pack current sensor B. The effect on battery current monitoring and control depends on the vehicle's system design.
At a glance
- Usually lights the warning light of the system that lost communication
- The engine or gearbox may go into limp mode
How it works
Hybrid/EV battery pack current sensor B measures battery current and sends its readings to vehicle control modules over the network. U064B sets when expected messages from sensor B stop arriving, leaving that sensor’s current data unavailable and potentially causing restricted hybrid or electric operation.
Common causes
Most likely first.
- Bus wiring open or shorted
- Module without power or ground
- Module failed
Symptoms
- Warning light or message related to the affected system
- Battery current data may be unavailable
How to diagnose it
- Scan all modules and record freeze-frame data, including high-voltage battery, current-sensor, isolation, and communication codes.
- Check live data for battery pack current sensor B and compare its availability with other reported battery data.
- Inspect accessible low-voltage connectors and network wiring associated with sensor B for looseness, corrosion, or damage without disturbing high-voltage components.
- Check the sensor B module’s low-voltage power and ground against the manufacturer’s specification.
- Test the network wiring serving sensor B for opens or shorts using the vehicle wiring information.
- If the circuits pass, verify sensor B’s network communication and module operation using the manufacturer’s procedure.
Common fixes
- Reconnect or clean an accessible low-voltage connector for current sensor B.
- Repair damaged low-voltage network wiring to sensor B.
- Restore the sensor B module’s low-voltage power or ground supply.
- Replace the current sensor B module if wiring and power are sound but it does not communicate.
Can I keep driving?
If a hybrid-system, battery, or reduced-power warning appears, stop safely and follow the vehicle’s instructions because propulsion may be limited or interrupted. Leave high-voltage components untouched and arrange prompt diagnosis.
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.