Because without a key, your Toyota vehicle will not allow any more keys to be programmed without changing the Engine Control Unit (ECU), the immobiliser and the smart box, which makes it a very expensive replacement. A replacement Toyota car key can cost in the thousands £££, so make sure you get a spare key NOW!
Toyota models manufactured post-1995 have an immobiliser system. This will shut off the engine if there is no correlating signal from the transponder microchip in the key and in some models the immobiliser is built into the key pick-up collar. However, Eydens Auto Locksmiths in Coventry can replace your Toyota key for these systems.