P1605 – Rough Idle / Idle Control Malfunction (Toyota)
Description
The ECM detected improper idle control operation resulting in unstable engine speed during idle conditions.
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Compare Diagnostic ScannersSymptoms
- Rough idle
- Engine shaking
- Idle fluctuations
- Possible stalling
- Poor acceleration
Causes
- Dirty throttle body
- Faulty idle air control valve
- Vacuum leaks
- Weak ignition components
- ECM idle learning lost
Diagnosis
- Inspect throttle body
- Check vacuum lines
- Test ignition coils
- Check idle control valve
- Perform idle relearn
Repair
- Clean throttle body
- Repair vacuum leaks
- Replace IAC valve
- Replace coils if needed
