[ckaiser]

Good morning. Getting F21. Have gone through much troubleshooting already. Have svc manual. Pump was replaced ~1-2 years ago.
Removed lower front panel and top. Visual inspection OK. Cleaned out drain pump filter. Found 3 coins, nothing in pump impeller. Pulled pump, verified impeller OK, reconnected motor out of housing, started drain cycle, pump spins. No blockage in drain hose, pump will evacuate all water except for the usual cup or two in the bottom.
Removed and metered pressure switch. All contacts show continuity at correct times.
Removed and checked pump-to-tub hose, all clear.
Checked water inlet valves, ~850 ohms.
Let sit unplugged for 20 minutes and then a cycle will start but eventually errors out with an F21 again. During cycle, dispenser motor operates and detergent clears out. I did not watch the cycle long enough to tell if it went through a spin or not.

Can anyone provide additional troubleshooting steps? Thanks!

[ckaiser]

Forgot to mention; during diagnostics, once past trouble codes, it goes to door locked, drain and spin, and sits there with pump running. after a few minutes, lights flash again and back to F21. Cannot get past that part of diagnostic test.
Thanks.

[ckaiser]

Update... After cleaning out the tub-to-pump hose, I also blew through the pressure switch tube. While it didn't seem clogged, everything is now working after 4 loads.
No changes were made to anything else, and since the pressure switch is one of the triggers on the drain cycle, logic dictates that the tube may have just been slightly clogged.

Will update again after a few more loads...