Prepare the dishwasher unit for the test cycle by simultaneously pressing the "Power Scrub Plus" and "Regular Wash" buttons when the dishwasher power button is turned off. Keep holding those two buttons down while then pressing the "On/Off" button as well. Release all three buttons simultaneously. You will see lights on all three buttons flash together to signal that the dishwasher is ready to start the test cycle.
Engage the test cycle by pressing the "Power Scrub Plus" and the "Regular Wash" buttons simultaneously, once more. The test will then run on its own and signal if a problem is found.
Interpret the lighting of the "Wash" button as a problem with the heater. Interpret a light over the "Rinse/Dry" button as a problem with water filling function, either too much or too little. Ascribe a lit "Clean" button to a fault in the temperature sensor also known as the NTC system.
End the test program at any point in the process by pressing down the "On/Off" button just once.