P1604 – Startability Malfunction (Toyota)

Description

The ECM detected repeated failed or extended start attempts, indicating a startability malfunction.

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Symptoms

  • Hard starting
  • Long cranking time
  • Rough idle after starting
  • Engine may stall shortly after starting
  • Check engine light may be on

Causes

  • Weak battery
  • Failing fuel pump
  • Clogged injectors
  • Vacuum leak
  • Worn spark plugs or ignition coils

Diagnosis

  • Check battery voltage
  • Measure fuel pressure
  • Inspect injectors
  • Check ignition components
  • Scan for related Toyota-specific codes

Repair

  • Replace weak battery
  • Replace fuel pump
  • Clean or replace injectors
  • Repair vacuum leaks
  • Replace worn ignition components