Mobile EV BJB / HVJB Repair London | FixAnyEV

⚡ EV Battery Junction Box (BJB / HVJB) Fault Repair in London

Fast, Mobile BJB / HVJB Diagnostics for All EV Makes & Models

The Battery Junction Box (also known as the BJB, HVJB or High‑Voltage Junction Box) is one of the most critical components in an EV. It controls the main contactors, pre‑charge circuits and HV fuses. When the BJB develops a fault, the EV may refuse to start, fail to charge, enter reduced‑power mode or shut down completely. FixAnyEV provides fast, expert mobile diagnostics anywhere in London to identify and repair BJB faults safely.

📞 Call 07779 836 677 for immediate assistance.

⚠️ A BJB fault can disable your EV instantly. ⚠️ Do not continue driving if you see HV system or contactor warnings. ⚠️ Never attempt to open HV components yourself.

Common BJB / HVJB Faults We Repair

Contactor Failure

  • EV won’t start
  • “Ready” light won’t appear
  • Clicking noises from HV system
  • Sudden shutdowns

⚠️ A stuck or welded contactor is a serious safety risk.

Pre‑Charge Circuit Failure

  • Charging stops immediately
  • “Pre‑Charge Fault” warnings
  • HV system unable to initialise
  • DC fast‑charging refusal

Blown HV Fuses

  • No power to inverter or OBC
  • EV stuck in “No Ready” state
  • Charging disabled
  • Multiple system warnings

⚠️ HV fuses blow for a reason — the root cause must be diagnosed.

Water Ingress in BJB

  • Moisture inside HV junction box
  • Isolation faults
  • Burning smell
  • Corrosion on terminals

⚠️ Water inside the BJB can cause catastrophic HV failure.

HV Cable or Connector Damage

  • Insulation breakdown
  • Arcing marks
  • Intermittent power loss
  • HV isolation warnings

BJB Communication Errors

  • CAN bus faults
  • “Electrical System Error”
  • Random resets or shutdowns

Our BJB / HVJB Diagnostic Process

  1. Full EV‑compatible scan – read HV system and BJB fault codes
  2. Contactor and pre‑charge testing – verify switching and ramp‑up behaviour
  3. Insulation and isolation checks – identify leaks or breakdown
  4. Physical inspection – connectors, seals, fuses and moisture
  5. On‑site repair or safe workaround – restore safe HV operation

⚠️ Never continue charging an EV that repeatedly stops due to HV faults.

Why EV Drivers Choose FixAnyEV

  • Mobile EV specialist covering all of London
  • High‑voltage certified technician
  • Advanced diagnostic tools for all EV brands
  • Faster and more convenient than a dealership
  • Clear, upfront pricing
  • Trusted across London, Surrey, Sussex and Kent

📞 Book now: 07779 836 677

Areas We Cover in London

We cover all London boroughs, including:

  • Croydon, Bromley, Lewisham
  • Camden, Islington, Hackney
  • Ealing, Brent, Hillingdon
  • Kingston, Richmond, Sutton
  • Central, North, South, East and West London

Book Your EV BJB / HVJB Repair

If your EV shows HV warnings, contactor faults or charging issues, FixAnyEV brings expert diagnostics and repair directly to you.

⚠️ BJB faults are safety‑critical — do not delay diagnosis. ⚠️ Stop driving immediately if the EV shuts down or limits power.

📞 Call 07779 836 677 to book your mobile EV repair.