Short Circuit

• An IAC motor can short circuit due to bad wiring or an overload of current, causing the motor to operate the valve more slowly or not at all, which in turn can result in the engine stalling at idle. Replacing the failed motor unit typically restores correct IAC valve function.
  
  

Carbon Buildup

• Over time, carbon can accumulate in the IAC motor, leading to poor control of the IAC valve and subsequent poor engine idling and stalling problems. Removing carbon or other sediment from the motor with cleaner typically corrects the IAC valve problem.
  
  

Bad Hose

• A vacuum hose connects the IAC motor to the intake manifold in some vehicle models. A torn hose causes the engine to lose vacuum, affecting how the IAC motor opens and closes the IAC valve.