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Critical· MBB / BMS log file

Contactor Stuck

Main battery contactor is welded or stuck closed

SystemSource: MBBLog file condition
Last updated: July 30, 2026

What it means

Main battery contactor is welded or stuck closed

CriticalSerious issue, immediate attention required.

This is a critical fault. Do not ride until it has been resolved.

Likely causes

  • High-current event welded contacts
  • Contactor mechanical failure

What to do

  1. 1Do not ride - serious safety issue
  2. 2Dealer inspection required immediately
  3. 3May require contactor replacement

Which bikes use this table

Recorded in the binary log rather than shown on the dash — every generation writes them.

Questions

What does "Contactor Stuck" mean in a Zero log?

Main battery contactor is welded or stuck closed. It is written by the MBB. It is classed as critical: serious issue, immediate attention required.

What should I do about it?

Do not ride - serious safety issue. Dealer inspection required immediately. May require contactor replacement.

See when this actually happened on your bike

A dash code tells you the fault; the log tells you the pack temperature, the state of charge and the ten minutes leading up to it.

Upload a log

Community reference: ZeroManual wiki entry

The code and its name are transcribed from Zero's own owner manuals; the severity, category and troubleshooting notes are ours. For official diagnostics, consult an authorized Zero Motorcycles dealer.