"pogulbowen" <pogul@hotmail.com> gurgled happily, sounding much like they
were saying:

According to my '96 XM handbook :-

Switch the ignition on, put the "old" code in.
Press "C"
Put the "new" code in.
Press "C"
You should get four flashes of green, and four beeps.

Next time you start, either old or new code will work, but whichever you use
will be the one "retained" for future use - in case you did a typo.

You've also got a "Service mode"
Ignition on.
Put the code in.
Press "S"
Put a different code in.
Press "S"
You should get six green flashes and six beeps.

Take the car to the garage, tell them this temporary code, and leave them to
do the service. When you get the car back, use your normal code, and the
service code is cancelled.

Saves you having to tell the dodgy mechanic chimps your "real" code.

Oh, and there's a big warning panel in the handbook - "Warning : If the code
is forgotten, the engine management system must be changed"....

Don't. Just DON'T forget it.