P1506 Idle Air Control Over Speed Error ?

The computer controls the idle speed via the idle air control valve on the intake next to the throttle body but the RPMS remain high. You need to check for vacuum leaks on any hoses to the intake or the gaskets at the intake and verify the throttle plate is not sooted and sticking open and throttle cable is not fraying and sticking. If all of these are good then a new idle air control valve needs to be installed while the negative battery cable is disconnected.So both possibilities needs to be checked, the iac valve as well as vacuum leaks.