OBD-II FAULT CODE
P1602

Immobilizer/ECM Communication Error

Reference information for P1602. Because this is manufacturer-specific, confirm the exact definition for the vehicle before using the diagnostic guidance below.

Manufacturer-specific code

This code can have different meanings depending on vehicle make, model and year. Treat the definition below as a reference and confirm it with OEM service information before diagnosis or repair.

PowertrainSystem
Network / communicationCategory
HighSeverity
  • Check Engine light
  • Poor drivability or reduced fuel economy depending on fault
  • Low battery voltage
  • Blown module fuse
  • Poor ground
  • Open/short on communication bus
  • Module offline
  • Scan all modules and record freeze-frame data before clearing codes
  • Check battery voltage and related fuses
  • Run a full system scan to identify modules not responding
  • Inspect CAN/SCP wiring, connectors and grounds
  • Repair power/ground or network wiring fault first
  • Only consider module replacement after wiring and power supply checks pass
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Disclaimer: Information is provided for general guidance only and may not apply to all vehicles. Always consult a qualified technician.