My dishwasher doesn’t clean as well as it always used to. It still goes through all the cycles, but only plates really seem to come out clean. Thinking the dishwasher might need a cleaning cycle, I ran a high-temp load with a bottle of cleaner. The dishwasher never got hot enough to melt the wax plug in the cleaner bottle. So I tested the heater element, hi-limit thermostat and thermistor in the OWI. All checked out fine per the service tech sheet. I even heated the thermostat and OWI in a pan of water to verify proper operation and resistance at the temperatures listed. So then I ran service diagnostics and got error codes 8-2 (Incoming water under 90°F), 3-3 (Thermistor/OWI failed calibration), 4-1 (Diverter: Control can’t determine position) and 1-1 (Control detected K2 relay stuck on). At the end of diagnostics, I got codes 4-4 (Diverter motor stuck on) and 4-2 (Reserved for future use). I proceeded to run diagnostics and clear codes in between running normal loads, and I seem to always get code 4-1 and occasionally 1-1, but never anything with the heating circuit.
If I run the sani-rinse option, that light always flashes after the load is done, so I checked the troubleshooting on the service tech sheet. Regarding codes 4-4 and 4-1, it says a diverter problem could be preventing water from heating.
Would replacing the diverter motor fix code 4-1 (is the diverter position sensor part of the diverter motor)? Also, the OWI senses soil every time during diagnostics even with clear water and a clean screen filter. Should I replace the OWI? And do I need to worry about the 1-1 code? Is there anything else I should test with the heating circuit? The tap water quickly gets up to about 120° F, so I know that's not an issue.
Thanks

Thanks for posting, you led me to our problem with our GU3600XTVQ1. Here's our story:

Our dishwasher started washing poorly, with greasy film left on the plastic dishes. We tried changing soaps, which helped a little but didn't eliminate the problem. I checked the wash temp and found it wasn't reaching 120 degrees during the wash cycle.

I pulled the error codes. During the diagnostic cycle, the diverter would run continuously when it was asked to move. I also noticed during the cycle there was a small water leak in the diverter motor region. The design is poor - if the seal leaks, it leaks on the switch and corrodes the diverter switch and connector (more on that later).

The diverter motor is available separately but the seal can only be replaced as part of the sump. I opted to change the seal since it's in a pressure area. I ordered a new sump assembly, since it was $50 more for the assembly and the wash motor and plumbing was included in the assembly. The other option was to buy the bare sump and diverter motor individually.

Change-out of the sump assembly was straightforward but a little time consuming. The connector for the diverter switch was pretty green with corrosion and I tried to clean it up but the diverter motor ran constantly and I got error code 4-1. I ended up ordering a new connector from Mouser. It is a Molex 91717-0008 connector but any 91717 series connector can be used and the extra keys cut off (I used 91717-0002 since that's what they had in stock). I cut about an inch off the wire for good measure and crimped on the new one (it is an IDC).

A week later, it washes dishes well again and has no error codes!

Thank you so much for posting 7 years ago! I was getting code 9-1 which is "can't find diverter position". I replaced the Diverter motor, but it didn't fix it. I did discover the grommet had been leaking by the corrosion on the connectors (intended to clean them up but forgot). I had figured out there was a position sensor, but couldn't figure out where that sucker was. After reading your post, I dug the old one out of the trash, and sure enough, there was the sensor, all corroded, and one lead was broken.
So I yanked that thing back out, cleaned up the connector, and all is well. Thank you so much!