Bosch dishwasher not heating
 

I have a 7 year old bosch dishwasher. I noticed today that the wash
cycle was taking a very long time (i.e 3 hours ) and when opened it
was cold. The rinse cycle is usually hot to dry the contents .

I assume that the heater is broken ? It will happily wash away,
presumably washing until some absolute timeout is hit, hence the
extended wash cycle.

Anyone else seen this kind of problem ? Coud it (hopefully) be
something as simple as an internal fuse ?