Our not yet five year old Bosch dishwasher has over the past couple of months developed a progressively louder droning noise. It’s not there all the time while washing and don’t know how to tell if it’s when it’s draining or taking water in when it’s happening. I’ve cleaned out the drain pump, spray arms and had a look at the impeller which all seemed fine. Any ideas/suggestions on what it could be would be much appreciated.
Could be a noise coming from the water inlet. You’ve checked the drain so now turn off the stopcock and unscrew the aquastop valve to check the filter. If the water pressure fluctuates during different times of the day and night then that could explain the random nature of the noise?