What does it mean?
When a code P0660 is stored in your OBD II equipped vehicle, it means that the powertrain control module (PCM) has detected an open circuit in the intake manifold air control (IMAC) solenoid circuit for engine bank one. Bank 1 indicates that the malfunction has occurred in the bank of the engine that contains the number one cylinder. The term open can be substituted for disconnected or broken.
The purpose of the IMAC system is to fine tune and regulate air flow as it enters the lower intake manifold, cylinder heads, and the combustion chambers. Controlled by the PCM, the air control solenoid opens/closes one or more flaps which fit snugly into the intake port of a particular (or multiple) cylinder. Sometimes intake manifold runner flaps, the IMAC flaps are attached to an electronic solenoid via a rod or shaft.
In some cases, the IMAC flaps are bolted to a thin metal rod that runs the length of each cylinder head and through each intake port. In this case, all of the flaps can be opened at the same time and with one solenoid. Of course, this also means that all of the flaps may be rendered inoperative by a single flap that is stuck or binding – or by a defective solenoid. Automakers utilize varying types of IMAC systems.
Always consult a reliable vehicle information source for the specifics of the IMAC system with which the vehicle in question is equipped. To determine whether the IMAC actuator is functioning properly, the PCM monitors input voltage signals from the IMAC solenoid, manifold absolute pressure (MAP) sensor, manifold air temperature sensor, intake air temperature sensor, throttle position sensor, the oxygen sensors, and mass airflow (MAF) sensor.
Once certain air intake, vehicle speed, and throttle position conditions are detected, the PCM adjusts actual air flap position accordingly. If the PCM doesn’t recognize a level of IMAC circuit voltage that is within preset parameters, a code P0660 will be stored and a malfunction indicator lamp may be illuminated. Multiple ignition cycles, with an IMAC actuator failure, will often be required for the MIL to be illuminated.