DTC P0506: Idle Control System Rpm Lower Than Expected: Description

The amount of air taken in during idling is regulated by the opening and closing of the servo valve located in the air passage that bypasses the throttle body. If there is a malfunction of the IAC system, the actual engine speed will not be identical to the target engine speed. The ECM (M/T) or PCM (A/T) checks the difference between actual engine speed and target engine speed.