BMW Repair: BMW 325i / starting issue, bmw 325i, time switch

Question
The car will start and run great when cold, but when I try to start it after shutting it off when up to tempreature, it will only start then shut off . Once it is cooled off it will then start again.

Answer
Peter,
 This could be caused by the "Thermo-time" switch located on the thermostat housing.  This sensor tells the cars computer (ECU) that the car is up to temperature.  When the car is cold it idles up the engine a bit to run smoother, and once it's up to temp it will idle back down (small ammount).  Your sensor could be faulty, telling the computer that the car is overheating or some other false signal.

 Check into this as it could be the problem.

 Good luck,
 Josh