Powertrain, generic (extended)

P2BC5 Battery Charging System Positive Contactor B Stuck Closed

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

P2BC5 reports that positive charging contactor B still conducts after the open command, normally because its contacts have fused. Mercedes-Benz stores it, often with P2BCC, in the DC charge connection unit (N116/5, on the eSprinter N24/6) of GLE, E- and S-Class plug-in hybrids, the EQB and the eSprinter; after a DC session the vehicle refuses to start. Bulletin LI47.70-P-079912 blames current ripple, overcurrent or overvoltage from the station and contacts that part too late, and prescribes a software update plus a contactor-fault reset rather than a new unit. Mazda lists it as OBC contactor (+) stuck on in CX-90 (from 2024) and CX-70 (from 2025) plug-in hybrids and swaps Junction Box No. 2 (30-003-26). The reverse fault is P2BC6, the minus side P2BCC.

Likely causes

Contacts of positive contactor B welded, e.g. after current peaks at the end of charging
Software of the charging module judges the contactor state wrongly (Mercedes update)
Ripple, overcurrent or overvoltage from the charging station
Coil driver does not switch off

Symptoms

  • Vehicle will not start after DC charging (Mercedes)
  • High-voltage or hybrid system warning in the cluster
  • Further charging blocked

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–4,000
Time0–10 h

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

Parts involved

bcs pos contactor bwiring harnessbms

Related codes

P2BC4P2BC6P2BCCP0E89P0D08

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.