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
