Skip to main content
zerologszerologs
Critical· MBB / BMS log file

ISO Fault

Insulation fault detected - high voltage may be contacting chassis

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

What it means

Insulation fault detected - high voltage may be contacting chassis

CriticalSerious issue, immediate attention required.

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

Likely causes

  • HV wiring damage
  • Moisture intrusion
  • Insulation breakdown

What to do

  1. 1Do not ride - serious safety issue
  2. 2Do not touch any HV components
  3. 3Dealer inspection required immediately

Which bikes use this table

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

Questions

What does "ISO Fault" mean in a Zero log?

Insulation fault detected - high voltage may be contacting chassis. 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. Do not touch any HV components. Dealer inspection required immediately.

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.