How do you Reset the immobiliser on my mondeo estate?

To reset the immobiliser on a Ford Mondeo Estate, first ensure that you have the correct key fob. Insert the key into the ignition and turn it to the "On" position without starting the engine, then turn it back to "Off" within 10 seconds. Repeat this process three times, ending with the key in the "On" position. Finally, turn the key to "Off" and try starting the engine; this should reset the immobiliser. If issues persist, consult your vehicle's manual or a professional.