How do I clear the F21 code?

Whirlpool says to press PAUSE/CANCEL twice, disconnect power, and check drainage. Clearing the display does not fix the cause. Follow your model manual before retrying. Request service if F21 returns.

Why does my Whirlpool washer keep showing F21?

Repeated F21 means draining still takes too long. Check reachable external hose sections, household drain backup and detergent use first. A pump fault is possible, not proven.

Can I still use the washer with an F21 error?

Do not keep adding loads while the washer retains water or shows F21. Stop for flooding, hot retained water or unsafe electrical access. Follow the manual or request service.

Is F21 the same as the SD or Sud code?

No. F21 concerns long draining; SD or Sud concerns excess foam. Excess suds can contribute to draining concerns. Review HE detergent use without adding more detergent to clear the fault.

Should I buy a pump for an F21 error?

Not from the code alone. The hose, household drain, detergent, internal blockage or sensing may be involved. Ask for a confirmed cause and model match before buying a part.

Whirlpool · Washer · Error code F21

Work this case — free pilot

Whirlpool washer F21 error code

likely causes and what to check

What it means

F21 means the washer took too long to drain. The control expected an empty tub within about 8 minutes and didn't get one, so it stopped and put the code on the display.

It usually shows up mid-cycle with water still standing in the drum. That water is the clue — how fast it leaves tells you which cause you are chasing.

Likely causes, ranked

Restricted external drain pathWhirlpool names hose restrictions and household drainage in its F21 checks
Excess sudsnon-HE detergent or too much detergent can interfere with draining
Internal drain obstructiona hidden blockage remains possible when external checks do not settle it
Drain pump faultpossible, but the error code alone does not confirm the pump
Water-level sensing faulta technician may need to check sensing when drainage looks normal

General concerns, not measured probabilities. In the free pilot, check outcomes reorder concerns without proving a fault is eliminated.

Verdict, in general terms

Try the manufacturer’s external checks before buying a part. They need no purchased parts. If F21 persists, get a diagnosis and written quote. Age, condition and local replacement costs decide whether repair is worthwhile. We cannot price a model-matched pump or recommend replacement from this code alone.

Stop for flooding, hot retained water, wet plugs or unsafe access. Do not open the cabinet or filter without model-specific user-repair instructions.

The checks, in order

3 checks

Check 1 — Inspect the reachable drain hose
5 minutes · torch
This eliminates: visible kinks or incorrect height; hidden blockages remain possible.
The step-by-step opens inside a case.
Check 2 — Look at the household drain
5 minutes · torch
This eliminates: visible drain backup or poor hose placement; not a hidden clog.
The step-by-step opens inside a case.
Check 3 — Review the detergent
2 minutes · detergent label
This eliminates: non-HE detergent or an excessive dose as a usage concern.
The step-by-step opens inside a case.

Stop line

Stop when the external checks do not settle F21, or access is unsafe. The WFW9400SU00 manual does not establish homeowner filter access. Do not remove its lower panel or inspect the pump internally.

What to tell the technician: "My Whirlpool washer shows F21. These are the external checks I tried and what changed. Please confirm whether the fault is household drainage, an internal blockage, the pump or water-level sensing."
What to ask: Ask for the diagnosis and a written parts-and-labor quote before approving a replacement pump. Ask whether the household drain was checked.
What a fair price looks like: We do not have a verified local quote or model-matched parts price. Compare the written total with another repair quote and the installed replacement cost.

Common questions

5 questions

How do I clear the F21 code?: Whirlpool says to press PAUSE/CANCEL twice, disconnect power, and check drainage. Clearing the display does not fix the cause. Follow your model manual before retrying. Request service if F21 returns.
Why does my Whirlpool washer keep showing F21?: Repeated F21 means draining still takes too long. Check reachable external hose sections, household drain backup and detergent use first. A pump fault is possible, not proven.
Can I still use the washer with an F21 error?: Do not keep adding loads while the washer retains water or shows F21. Stop for flooding, hot retained water or unsafe electrical access. Follow the manual or request service.
Is F21 the same as the SD or Sud code?: No. F21 concerns long draining; SD or Sud concerns excess foam. Excess suds can contribute to draining concerns. Review HE detergent use without adding more detergent to clear the fault.
Should I buy a pump for an F21 error?: Not from the code alone. The hose, household drain, detergent, internal blockage or sensing may be involved. Ask for a confirmed cause and model match before buying a part.

Stuck, or want a person?

Ty Fletcher answers a Second Opinion by email within 24 hours — 10 years of construction and maintenance, not a licensed technician. You send photos and the model plate; the answer names the next thing to do, or the stop line.

Get a Second Opinion — $49One payment. Answered by email.

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