I lost key to car and bought new one from Jag car won't start. on 1991 Jaguar Vanden Plas

Key goes in fine but car won't turn over. How do you get it to reset for the new key ?

Asked by for the 1991 Jaguar Vanden Plas
Do you mean it won't start(run) , or won't crank(where the engine actually spins). Does the car have any aftermarket security installed. When you bought the key from the dealer did they say , or did you inquire about , whether or not the key NEEDS to be programmed ?