£10 + http://www.focusstoc.com/forums = your be glad ya did

Right jump in car, on indicator stalk hold the reset at same time turn key to 2nd click display will flash up test mod, 1st it will do a gauge sweep, then using scroll keep flicking till u come too DTC an under them letters it should say #NONE.... so least u can rule out its not a spot specific fault.

After that, are u sure fob battery ok??

Not sure where the alarm pick up is in car, THINK its around interior light cluster but could be that...

Follow my above link, best £10 you wil spend on the ST