Code P0505 - Idle Control System
- Possible causes of Code P0505 are IAC valve, fast idle thermovalve, clogged port in throttle body, vacuum leaks, incorrect input from ECT sensor, and incorrect input from throttle position sensor. Inspect and correct these items as necessary.
- Connect and operate scan tester, following manufacturer's instructions. Run engine at 3000 RPM until fan comes on, then allow it to idle. Read throttle position. Throttle position should be approximately 10 percent. Read engine coolant temperature. Engine coolant temperature should be 194-221°F (90-105°C). If throttle position or engine coolant temperature are not within specifications, repair appropriate sensor circuit.
- Read idle speed under no-load conditions: with headlights, blower, rear defogger, and radiator fan not operating. If idle speed is not 650-750 RPM, go to next step. If idle speed is 650-750 RPM, problem is intermittent, but system is okay at this time.
- If idle speed is 650 RPM or less, go to next step. If idle speed is not less than 650 RPM, go to step 6).
- Unplug 2-pin connector from IAC valve. If engine speed drops or engine stalls, adjust idle speed. If idle speed cannot be adjusted, clean ports at throttle body. If engine speed does not drop, temporarily substitute known good IAC valve, then retest system.
- Turn ignition off. Remove cover from fast idle thermovalve. Start and idle engine. Feel for airflow at valve seat. If airflow does not exist in valve seat area, go to next step. If airflow exists in valve seat area, check coolant level and for air in cooling system. If all is okay, temporarily substitute known good fast idle thermovalve, then retest system.
- Inspect for vacuum leaks. Ensure throttle valve closes fully. Adjust idle speed. If idle speed cannot be adjusted, temporarily substitute known good AIC, then retest system.