thank you for your advice and it does make sense, but i am still in a quandry as to why the check engine light comes on each time the fluid is low and stays on until the fluid is topped up. this makes no sense to me at all. i pulled the pads off the front and found the drivers side with about 50%wear[normal] and the passengers side almost to metal. ther was no sign that the caliper was sticking, although not much else would cause this uneven wear. in any case i replaced the front pads and will keep an eye on it as i am really not much wiser. if anyone has any ideas let me know and if not thank you for your help so far sam