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P1631 – Theft Deterrent Start Enable Signal Fault

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Symptoms

  • No start
  • Security warning

Causes

  • Immobilizer fault
  • Wiring issue
  • ECU issue

Diagnosis

  • Inspect wiring
  • Scan immobilizer
  • Check ECU

Repair

  • Repair wiring
  • Replace immobilizer
  • Repair ECU
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