We have had this issue for the past couple years and the solution has been to clean the heating element in the back of the dryer. The element clogs up with lint and some of the lint shows evidence of burning. There are two sensors here and and they shut down the element. Safe guard system. After carefully cleaning out the lint and reinstalling the the heating element the dryer works like it was new.
My issue with this, is that Bosch's lint collection system design is extremely poor. Lint should not be bypassing the filter and getting into places it should not be! If you take on the challenge of opening up the dryer you will be shocked by how much lint has accumulated through out the rest of the dryer. We now clean the dryer out completely every 6 month's. Which means opening all the panels. Top/ back & sides. The heating element on the back of the dryer is easy to take off. A couple torx screws (6 to 8). You need to take the cover off the box that protects the heating element, these are tabs that fold over. When you unfold the tabs the heating element will fall out so be very careful. (This should go with out saying, but I will say it anyways, unplug the dryer before attempting the cleaning) To clean the elements we use a tooth brush. Take care to not damage the elements and they "should not touch each other". We are a family of 4 and laundry is done once a week and the lint screen is cleaned after each load. We took pictures to send to Bosch and have not completed our e-mail. I personally believe this is a design issue that Bosch has missed. Unfortunately the fix is major and therefore nothing will be done. My faith in Bosch and the quality, we as consumers have come to expect was missed in the development of this dryer. My biggest concern is a fire from the lint blockage on the heating element, safe guards or not, the risk is there.