My Whirlpool dishwasher (wdf520padm3) started leaving food on dishes and not drying dishes as well as it used to, even when I ran the 'high temp' and 'heavy' cleaning options. This started happening after about 3 years of operation. To try to diagnose the issue, I started the diagnostics cycle (see below for instructions on how to do this). However, the 'Clean' LED is also not working on my dishwasher, so I was unable to read the error code after the service cycle finished.
I decided to replace both the heating element and the high limit thermostat, both of which I ordered from AppliancePartsPros. I followed the Youtube videos here:
https://www.youtube.com/watch?v=xX5-ruvqZaI
https://www.youtube.com/watch?v=YfUK6OfTFFc
I have 0 experience working on dishwashers, and it took me about an hour to disconnect all the water/drain pipes, electrical, and actually get the dishwasher out of the cabinet.I recommend you take pictures of the electrical wiring before disconnecting so you know exactly how to put it back. Once the dishwasher was out, it was easy to replace the two parts, and getting the dishwasher back in was easier than getting it out now that I knew what to do.
I tested the dishwasher afterwards, but was disappointed that the water still didn't seem to be heating enough, and running the sani-rinse option finished with a flashing 'Sanitized' light (meaning the water was not heated to the proper temperature). I found a blog with a report of a similar issue here:
https://www.applianceblog.com/mainforums/threads/wdf510paysa-sanitized-light-blinking-at-end-of-cycle.61627/
Requoting below in case the website goes away:
"Anytime you replace a part on these new dishwashers you always have to run the SERVICE DIAGNOSTICS CYCLE, and let it run all the way through to reset it back to default.
Entry sequence: Press any 3 keys in the sequence 1-2-3, 1-2-3, 1-2-3 with no more than 1 second between key presses. NOTE: Some models have replaced the “Clean” LED with “Completed.”
The Service Diagnostics Cycle will start when the door is closed. Invoking Service Diagnostics clears all status and last run information from memory and restores defaults. It also forces the next cycle to be a sensor calibration cycle. LET IT RUN ALL THE WAY THROUGH: Service diagnostic cycle will take about 23 minutes."
I ran the service diagnostics cycle, then tried sani-rinse again. Water was heated to the proper temperature (solid 'Sanitized' light now) and everything seems to be working now.
Afterwards I tested the continuity of the removed heating element and found that it was faulty, so that was probably the issue.