In RobotC is there anyway to enable a failsafe?
i.e. - trigger a digital port to go high when control signal is lost?

im am building a gas powered RC car, that has a relay connected to a digital port to short the magneto to kill the engine on command, but i also want it so that when i go out of range of the controller, the robot does not keep going, and the engine stops. any help is greatly appreciated.

There’s a variable that you can check to determine which of the two RF channels to the (Crystal) transmitters are being received by the VEX Master processor. You can use this to then set a digital output port.