I bought this car around a year ago, it works fine on a day to day basis but if I try to go on the motorway and go over 70mph the engine light will start blinking, if I drop it back down to below 70mph it goes off and stays off, the car will then continue to run fine as long as I don't go over 70mph. I have taken it to a garage who have plugged in a diagnostic machine but no error codes are coming up, does anyone have an idea of what it could be as I would like to get this repaired before something major happens to the engine?
Thanks