Product review (5 stars): APS works great -- but may not be the solution
My Whirlpool Duet washer displayed SUD and F35 errors. Turns out this is a common problem. Most people believe this to be the fault of the Analog Pressure Sensor (APS) and most people replace it. I did so and it worked -- but now, three years later, the problem repeated.

Replacing this part is straight forward. Unplug the washer, unscrew and remove the top. Turn the old part 90 degrees counter-clockwise to pull it away from the washing machine holding notch and then gingerly remove the wiring harness from the old part. Attach the wiring harness to the new part, insert the part into the holding notch, and turn it clockwise 90 degrees -- job done. Three years ago when I did this it took longer but this time it was easy -- a ten minute fix with most of that time fiddling with the harness.

This time, after installing the new part, the error codes remained. I did some more web searching and found an answer. The real issue is a pair of  fried capacitors. Search YouTube for Jarred Johnson's "New and Improved. Fix your Whirlpool Washer with "SUDS" and F35 error" -- it explains what's happened and why and what to do.

The fix entails getting to the Control Panel Unit (CPU) and replacing two faulty capacitors, rated 2200uF/10v, with 2200uF/25v units. You may source the replacement capacitors locally from an electronics store (for under a dollar each) or order online (factor in handling & shipping).

Getting to the circuit board is a bit of a chore, at least for me. You'll have fun dislodging the CPU from the washer, removing the plethora of wiring harnesses, and opening the housing unit which houses and protects the circuit board. But with some thought and care and determination (and perhaps choice but misplaced colorful language) it can be done. When I finally got to the capacitors I could clearly see the slightly distended tops -- a sure sign of fried/blown/shot/overextended capacitors.

I had to borrow a soldering iron because I couldn't find mine (hadn't used it in years) but just could not dislodge the last bit of solder, even with a solder sucker. In the end, I took the board to a local tv repairman who replaced the capacitors for $10 -- parts and labor -- in about two minutes. (He just heated that soldered hole and slid in the new capacitor lead wire which slipped right in -- real easy once you see it done.)

With the faulty capacitors replaced, my Duet washer works good as new.

So. You can buy this expensive APS and maybe get temporary relief -- or go the extra mile and dig out that circuit board and replace the capacitors for a lot less. As I mentioned earlier, the APS solution worked for me for three years but this one may be the ultimate fix up front.