Network, generic

U064B Lost Communication With Hybrid/EV Battery Pack Current Sensor B

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

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.

Likely causes

Bus or supply wiring of sensor B damaged

Current sensor B failed

Missing or faulty CAN termination in the pack sub-network

Symptoms

Battery system warning lamp
Correlation check between the current sensors no longer possible
Possibly reduced charging or drive power

Repair estimate

DifficultyShop_onlyWorkshop job

Parts and labour€150–2,000

Time1–5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

hv battery current sensor bvehicle bus wiring

References: law.cornell.edu, lem.com.