Thats the problem with people not closing a topic, if anybody searches for it they dont find a answer.
If you are talking about the red service engine soon light on a DI there is a relay under the passenger kick panel with a Land Rover sticker on it, take a paper clip and poke a hole in the sticker and "short" the relay, it will reset the light.
There is a good write up on it on www.discoweb.org under the "tech" section.

 

So, the only way to clear a code is to read it, fix it then clear it with a scanner, been that way on all vehicles built since 1996.

 

There are TWO lights on a DI, a amber "check engine" light and a red "service engine soon" light.
The red one is a emissions service reminder.
The amber one is the trouble code one.

 

The key has to be on to do it...