2004 X type Jaguar keeps going into limp mode
That's strange, but first thing I would look at is the condition of your battery. Sometimes when the battery gets old weird things happen. How old is your battery, voltage? Should be 12.3 or higher and no older than 5 years. You can have it checked out for free at any local auto parts store.
Search Jaguar X-TYPE Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Jaguar X-TYPE Experts