2006 Mazda MPV ESFACTORY OEM SERVICE PROCEDURE

DTC P1602: Notes

DTC P1602 [AJ] DETECTION CONDITION AND POSSIBLE CAUSES

DTC P1602 Immobilizer unit-PCM communication error
DETECTION CONDITION 
  • Command transmission from the PCM to the immobilizer control module exceeds limit.
  • No response from immobilizer control module.
POSSIBLE CAUSE 
  • Immobilizer unit malfunction
  • Coil (immobilizer system) malfunction
  • Key (transponder) malfunction
  • PCM malfunction
  • Open circuit in wiring between immobilizer control module terminal A and PCM terminal 64
  • Open circuit in wiring between immobilizer control module terminal C and body ground
  • Open circuit in wiring between immobilizer control module terminal F and coil terminal A
  • Open circuit in wiring between immobilizer control module terminal D and coil terminal C
  • Short to ground circuit in wiring between immobilizer control module terminal A and PCM terminal 64
  • Short to ground circuit in wiring between immobilizer control module terminal F and coil terminal A
  • Short to ground circuit in wiring between immobilizer control module terminal D and coil terminal C
G04327946Courtesy of MAZDA MOTORS CORP.
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

Shop Manual-Ready ToolsCompare Repair QuoteQuote Shield Pro

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.