DTC P0505: Idle Control System Malfunction (2000-2003 models)

NOTE:

If DTC P1519 is stored at the same time as DTC P0505, troubleshooting DTC P1519 first, then recheck for DTC P0505.
Before you troubleshoot, record all freeze data and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).

Start the engine. Hold the engine speed at 3,000 RPM without load (in neutral) until the radiator fan comes on, then let it idle.
Check the engine speed at idle without load conditions: headlights, blower fan, radiator fan, and air conditioner off.
Is the idle speed 800 +/- 50 RPM?
1. YES - Intermittent failure, system is OK at this time.
2. NO - If the idle speed is less than 750 RPM, go to step 3; if it is 850 RPM or higher, go to step 4.
Disconnect the idle air control (IAC) valve 3P connector.
Dose the engine speed increase or fluctuate?
1. YES - Check the idle speed with a different load condition (electrical, A/C, etc.). If it is out of specification, replace the IAC valve (see SPECIAL TOOLS ).
2. NO - Replace the IAC valve (see SPECIAL TOOLS ).
Turn the ignition switch OFF.
Remove the intake air duct from the throttle body.
Start the engine, and let it idle.
Put your fingers on the upper and lower ports (A) in the throttle body.

Fig 1: Identifying Fingers On Upper And Lower Ports (A) In Throttle Body
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Does the engine speed drop below 750 RPM?
1. YES - Check the idle speed with a different load condition (electrical, A/C, etc.). If it is out of specification, replace the IAC valve (see SPECIAL TOOLS ).
2. NO - Check for vacuum leaks at these parts:
  - PCV valve
  - PCV hose
  - EVAP canister purge valve
  - Intake manifold
  - Throttle body
  - Brake booster hose