WM4000 LG washer stuck stalled on 5 or 9 minutes SUD error

Описание: WM400 WMHWA LG front load washer issues with timer getting stuck on the rinse and spin cycle, eventually ending after an hour or so with or without a SUD error code? The washer is just about 2 years old from the purchase date. This was the fix for us. It took 3 service visits compliments of extended warranty to figure it out.
Here are some of the things checked to troubleshoot that did not work:
*no clogs in drain hose or pump trap
*no suds or foam in the water drained from the tub or in the pump trap/filter
*drain hose height to house drain - we actually bought hose to make sure it had the right height since ours sits on a pedestal
*not too much soap - we were using down to about 2 tablespoons of liquid! Truly dirty loads would take a few washes. SUD error would definitely pop up after about an hour to an hour and a half of trying to rinse when that happened
*shock absorber struts were not loose - all were tight, we even compared them to a new one we bought to see if they needed replacing
*warranty replaced the stator for the motor with a speed sensor
*ran several cleaning cycles with and without Affresh tablets
*ran smaller loads
*ran larger loads than normal
*water from house to washer was good
*no balance issues - rock solid even on fastest spin setting
*ran loads with just soap, no softener or bleach or Oxi-clean

At one point on the third visit the tech did get an error on a test for water flow but he said it was filling fine. He even popped off all of the hoses during a cycle to check that they were flowing correctly (they were).

So either (or both) the pressure sensor or PCB was the fix. I'd read some washers use a pressure sensor for the SUD error, but I do not know if this LG washer uses that in this case. The timing circuit is in the PCB so that might have been the issue.

Hope this helps if anyone else is troubleshooting. None of the forums or other videos that I could find provided a true solution. One other step we tried that didn't work were various power resets by unplugging from just a few minutes to overnight.