Originally Posted by Volasko
Check to see if the T-stat is plastic or aluminum. It is common to swap the t-stat when you do the pump and the updated design is plastic vs the originals aluminum. If you have an 06 and your t-stat is plastic someone must have swapped it already. See this thread for more detail:
the 9th pic is the t-stat shown in the original aluminum material. The 20th pic shows the updated plastic design.
BMW Canada tells dealers not to replace the t-stat and pump together (unlike BMW USA). The t-stat is replaced only if it has failed too - usually if the car repetitively overheats and the t-stat melts its electronics. You could coneivably have an old t-stat and a new pump, if the pump alone failed while the car was in warranty, or in CPO warranty.