Powertrain, generic · Hybrid propulsion

P0B4F Hybrid/EV Battery Voltage Sense E Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Cell sense channel E is the fifth measuring path between the battery cells and the monitoring electronics; P0B4F means the controller sees it as electrically open. Ford's experience shows how serious this can be: on 2019-2020 Fusion plug-in hybrids P0B4F appears among up to fourteen open-line codes from P0B3B to P0B7C with a no-start condition, and the bulletin prescribes replacing the high-voltage battery. On the 2023 Mach-E and E-Transit the same family points to an intermittent flexible circuit at the BECM. GM's BECM logic needs 0.6 s of an open-line pattern, such as adjacent cells 1.3 V apart or a balanced cell under 36 mV, and stores the code as Type A.

Likely causes

Broken channel E sense lead, splice or bus bar contact
Internal failure of the high-voltage battery (Ford Fusion PHEV)
Intermittent BECM flexible printed circuit (Ford Mach-E, E-Transit)

Symptoms

  • No start
  • Battery cannot be charged
  • Stop Safely Now message while driving

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–9,000
Time0–10 h

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

Parts involved

hv battery voltage sense ewiring harnessbms

Related codes

P0B50P0B51P0B52P0B53P0B4AP0B54

References: static.nhtsa.gov, static.nhtsa.gov, gsi.ext.gm.com, law.cornell.edu.