Abstract: A system is provided for automatically shutting off a running internal combustion engine after a predetermined length of idle time has occurred, for installation into a vehicle having electronic diagnostic and control computers incorporated to the vehicle. A first switching apparatus is provided, having open and closed modes for disabling and enabling the ignition system respectively. A second switching apparatus is provided, having open and closed modes for disabling and enabling the ignition system. A data collection device receives data from the connected vehicle diagnostic port including: battery level, engine RPM, vehicle speed, door ajar status, ambient temperature, handbrake status and brake pedal position. A computer is programmed to determine if the data from the diagnostic port set up the prerequisites to safe shutdown engine running operation, and to signal the first and second switching apparatuses to shut down the vehicle engine.