I have a Thermador Dishwasher (Made by Bosch) and have a similar problem. I found on this web site under dishwasher repair a PDF titled trouble shooting bosch dishwashers. In that document it has several trouble shooting tips and several testing proceedures. I found that the solder Joint on the control board got hot and now has a cold solder joint.I thought that I found the problem which was a problem also. After finding that problem I decided to look at the other things that were connected with the long run times and luke warm tempratures. Before I found the troubleshooting guide I thought that the problem was surely the heating element but when I tested it I found it to be good. The test that I did that was recomended was to check the resistance of the NIC which is a thermocouple. The resistance changes as the temp increases. The test was to check the resistance when it was room temp. At room temp it should have registered 55 ohms, mine registers nothing. It is open and the heating element cannot work if the NIC is open. I priced a new NIC at AppliancePartsPros.com
and it is about $35 bucks. The file I downloaded is bosch%20dishwasher%20troubleshoot.pdf. It might help you determine the problem so you can order the correct part you need.