I found my master key is worn out after 9 years use. I have to push the button several times and with great difficulty before it unlocks the doors for example. It did replace the battery with little effect. I just bought the car about 2 months ago, 4th hand I think. Where can I buy a second hand one in good condition? Or do I have to buy a new one from a Jaguar dealer, I presume they must key the car's security code or something into it? I am just looking for the most economical way to do it as my circumstances changed financially after I bought my car, and I now have to turn every penny around to survive and keep the car. Thank you in advance for advice and THANK YOU for this great forum!

 

You can buy them on ebay, but you will need to have the dealer or a specialist lock smith do the programming for both fob and key you can separate the key and fob, I'd get two fobs and one new key if it was me.
You will find masses of info on this by searching the S Type section.

I suppose I should mention the new members section one more time.

 

Have you tried taking it apart and cleaning it? You can also buy replacement microswitches for next to nothing on eBay.

 

You can lead a horse to water Norri!

 

As Norri mentioned, the key device is called a "FOB". Do a search on this forum for "FOB" as many other members have posted the fixes that work.

 

Put the key in the door lock and turn it like the plebs do on their Hondas.

 

You can take the fob apart and clean the micro switches with some electronic contact cleaner. That's what worked for me.