DTC P0506: Idle Control System RPM Lower Than Expected (2004 model)

NOTE:

If DTC P0511 is stored at the same time as DTC P0506, troubleshoot DTC P0511 first, then recheck for DTC P0506.
Information marked with * 1 applies to K20A3 engine; * 2 applies to K20A2 engine.

Start the engine. Hold the engine speed at 3,000 RPM without load (in Park or neutral) until the radiator fan comes on, then let it idle.
Check the engine speed at idle without load conditions: headlights, blower fan, rear defogger, radiator fan, and air conditioner off.
Is the engine running at 650* ¹ (700)* ² +/-50 RPM?
1. YES - Intermittent failure, system is OK at this time.
2. NO - Go to step 3.
Turn the ignition switch OFF.
Disconnect the IAC valve 3P connector.
Start the engine, and let it idle.
Check the engine speed at idle without load conditions: headlights, blower fan, rear defogger, and air conditioner off.
Does the engine speed increase or fluctuate?
1. YES - Check the idle speed with a different load condition (electrical, A/C, gear position, P/S, etc.) (see IDLE SPEED INSPECTION ). If it's out of specification, replace the IAC valve (see THROTTLE BODY DISASSEMBLY/REASSEMBLY ).
2. NO - Replace the IAC valve (see THROTTLE BODY DISASSEMBLY/REASSEMBLY ).