What should I check first for Whirlpool washer error F21?

Check the drain hose is not kinked.

F21Medium

Whirlpool washer error F21

F21 indicates a drain problem.

Also shows as F2 1

Symptom
F21
Free checks
4 checks
Then the part
Drain hose kinked

The 4 free checks

Start at the top. Unplug the machine first.

01
Check the drain hose is not kinked.
02
Check the drain hose is not clogged.
03
Unplug the washer for 5 minutes, then plug it back in to reset the control.
04
Clear the large-item filter in the drain pump — the code is reported when the washer has failed to drain within 8 minutes.

What causes it

Listed most likely first.

Cause	How often	DIY
Drain hose kinked	Most common	Yes
The drain path is clogged or restricted	Most common	Yes
Drain hose clogged	Common	Yes

Before you check anything

Disconnect the power first. Unplug the machine at the socket, or switch off its circuit at the consumer unit if it is hard-wired. Do this before opening any panel, reaching into a pump filter, or moving the appliance.
Turn off the water before disconnecting a hose, and have a towel and a shallow tray ready — a drain hose holds water even when the drum looks empty.
Gas, mains wiring and sealed refrigeration are for a qualified professional — in many countries that is a legal requirement, not advice. If you smell gas, do not touch any switch: leave, and call your gas emergency number from outside.
Stop if you smell burning, see scorched wiring, or find water near an electrical connection. None of those is a code to look up.

The checks on this page are the manufacturer’s own, rewritten and sourced, and they are reference information rather than a repair instruction for your particular machine. Model, age and installation all change what is safe to do. You are the one standing in front of it — if a step looks wrong for the machine you have, trust that and call a technician.