So we have two original XK8 ignition keys (black) and two key fobs. Fob #1 works, but sometimes takes several button presses to lock or unlock the doors. The second fob does not activate the door locks at all (despite new batteries), but will unlock the boot. Any ideas what may be causing this behavior?

 

After a forum search, I found the programming steps for the fob. I will try that tomorrow.

 

Don't try and reprogram the fob. As some of the buttons work (even intermittently) it means the fob is already programmed to the car. Most likely the contacts inside the fob are dirty or worn - see the attached document,

 

The contacts inside my fob are a very poor design and it is sometimes very difficult to get a good contact. I only managed it by adding a thin washer as a spacer.

Also, check carefully whether your fob requires a CR2032 or two CR2016's. People sometimes put in a single 2032 because they think that equals two 2016's and they do fit properly. However, the two configurations are not interchangeable.

Richard

 

BRAVO! Thanks for the tip, dibbit. Worked like a charm!

RichardS, Yes, double CR2016 batteries installed (+ side down)