An automated vehicle shutdown and user notification method and device for shutting down an engine in a vehicle having a passive keyless entry and start ignition system where the engine has unintentionally been left running by the user is disclosed. In one aftermarket embodiment, the method is implemented in an aftermarket remote start interface module. The module comprises a micro-controller, a memory, a vehicle data bus connector that provides for interface through the vehicles onboard diagnostic (OBDII) port to the vehicle data bus. The system includes a remote start module having a radio frequency transceiver and a cellular telephone transceiver, and provides audible, visual and electronic notifications that the vehicle has been left running and that the engine will be shut off unless the shutdown sequence is deactivated. If the shutdown fails by any malfunction, the system will go into an alternative notice mode.