Hi Tom, I had the same problem when I purchased my XM. The dealer fitted a new speedo head and it was fine until the warranty ran out! My local Citroen dealer in my village fitted a new sender unit on the gearbox but that did not work either. It sometimes works if you give the top of the dashboard a hard bang, which suggests a bad contact behind the panel. As there is a printed circiuit there perhaps there is a dry joint or one of the tracks on the board is broken. My car is going in to the village garage again but I am not too confident. Regards Gordon