Bosch Corporation programs a diagnostic test protocol into the computer that manages their dishwasher operations. The test cycle is designed to help identify problems and narrow down possible causes of malfunctions, so that repairs are targeted and correct. The single program is designed to run through multiple operations in sequence, including draining, water sensor calibration, filling, heating and circulation. The test program will pause and signal if the test encounters a malfunction in the system. Directions for operating the test protocol can vary slightly by model and control panel design, but the multistage test process remains the same.
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.