U064B code meaning
Lost Communication With Hybrid/EV Battery Pack Current Sensor B
Network system Generic code U06xx codes Check engine light
What U064B means
Some packs carry a second current sensor, B, often a different measuring principle than A, so that the battery controller can cross-check the two through P0B13 and still have a value if one fails. U064B is stored when that second digital sensor goes silent. No manufacturer publishes U064B. With only one remaining sensor the controller loses its redundancy; depending on the safety concept it may keep driving with sensor A but flag the fault, or reduce power until the plausibility check can run again. Sensors like LEM's CAB family send their readings as periodic CAN frames, so a missing frame stands out quickly. Section (e)(15.2.3)(A)(iv) of the CARB rule covers this input as well. An analog sensor B would instead log circuit faults P0B0E to P0B12.
U064B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyWorkshop only
- Typical labor1 to 5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U064B
- Battery system warning lamp
- Correlation check between the current sensors no longer possible
- Possibly reduced charging or drive power
Common causes of U064B
- PossibleBus or supply wiring of sensor B damaged
- PossibleCurrent sensor B failed
- Less likelyMissing or faulty CAN termination in the pack sub-network
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv battery current sensor bVehicle bus wiring
What each part of U064B means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 4B | The exact fault in that area. |
What to do next
- Note U064B and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U064B
What does U064B mean?
U064B means "Lost Communication With Hybrid/EV Battery Pack Current Sensor B". Some packs carry a second current sensor, B, often a different measuring principle than A, so that the battery controller can cross-check the two through P0B13 and still have a value if one fails. It is a generic code, so it means the same on every make.
Is it safe to drive with U064B?
Drive gently and only to a workshop. With U064B the car can go into limp mode (reduced power) to protect itself.
Will U064B fail an emissions test?
Yes, it can. U064B is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U064B to fix?
Difficulty: workshop only. A typical repair takes 1 to 5 hours of work. This is a job for a workshop.
Will U064B clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.