DTC P0506: Idle Control System, Rpm Less Than Expected: Condition

DTC is set when actual engine speed is 100 RPM less than programed target speed for more than 14.1 seconds with brake pedal depressed and front wheels in straight ahead position. This is a continuous monitor. MIL is illuminated when PCM detects malfunction during 2 consecutive drive cycles. Possible causes are:

• A/C relay control circuit malfunction.
• Air filter or intake passage plugged.
• Idle Air Control (IAC) valve malfunction.
• Low engine compression or too much blow by.
• Generator control circuit malfunction.
• PCM malfunction.
• Purge solenoid valve malfunction.