If your citroen is one of the early c5s (2001-2004) and what you are referring to is on the green screen in the centre of the dash, then what you are seeing will be the secondary read-out of the mileometer. This represents the distance travelled from the last re-set of the car's multi-function display (where you can view the date, current MPG, average mpg, average speed etc.). These screens are cycled using the button on the end of the wiper stalk, and can be returned to zero with a long press on this button. Note that when you return one of the screens to zero, it will zero all the readings or display --- until you do a few miles.
This is not an indication of any fault with the vehicle, merely an FYI message.
Hope this helps.
andy b, April 2008
