We have a Bosch Dishwasher that is not heating up. Sometimes when it is not working it gives an E02 error. I can tell from surfing that E02 can be a number of things in the electrical/control systems keeping it from heating the water, including the controller, but possibly wiring, thermistor, and heating coil.

Our house has hot-water on demand, and it takes some time for it to heat up and get to the kitchen. I believe that if the hot water is "ready", the dishwasher will run to its full cycle (but still not heat the water and dry the dishes). If the dishwasher starts without hot water, then I get the E02 error about 7 minutes into its cycle.

My question is whether this is a clue that can help me determine what is and is not broken? Replacing the control panel seems relatively easy, the rest of the fixes look far more complex and much more disassembly needed. I'm wondering if the odds are high that it is the controller and if this symptom helps deduce what is specifically broken.