The C-21 error on your Samsung Washer means the machine has detected a drainage problem — it’s either taking too long to pump water out or isn’t draining at all. Fix hint: this is almost always caused by a blocked drain filter, a kinked hose, or a faulty drain pump, and most people can clear it themselves in under half an hour.

Error code C-21
Meaning Drain error — the washer cannot remove water from the drum within the expected time
Severity Medium — the wash cycle will pause or stop until the blockage is cleared
Time to fix 15–40 minutes
Tools needed Towels, a shallow container, pliers (optional)

What the C-21 error means

Samsung washers monitor how quickly water leaves the drum during the drain phase. If the pump runs but water levels don’t drop as expected within a set time, the control board flags C-21 and halts the cycle to prevent overflow or motor damage. This code points to a physical obstruction or drainage flow problem rather than an electrical fault, though a failing pump can also trigger it.

It’s similar in nature to other flow-sensing faults like the Samsung Washer DE Error Code, where the machine reacts to something outside its normal operating range rather than an internal component failure.

Common causes

  • Debris, coins, or lint clogging the drain filter or pump housing
  • A kinked, crushed, or blocked drain hose behind or under the machine
  • The drain hose positioned too high or with an improper loop, restricting flow
  • A worn or jammed drain pump impeller
  • A blocked or slow household drainpipe or standpipe the washer empties into
  • Excess suds from using too much detergent, which can slow drainage

How to fix the C-21 error

  1. Power down and unplug the washer: Always disconnect power before accessing the pump or hoses to avoid electric shock.
  2. Check and clean the drain filter: Open the small access panel at the bottom front of the machine, place a shallow container underneath, and slowly unscrew the filter cap to release trapped water. Remove any coins, buttons, or lint, then rinse the filter before replacing it.
  3. Inspect the drain hose: Pull the washer out and check the hose for kinks, tight bends, or blockages. Straighten it out and make sure it isn’t pushed too far into the standpipe.
  4. Confirm the drain height and loop: Make sure the hose end sits between 24–96 cm off the floor with no upside-down loop that traps water — the wrong height can stop proper siphoning.
  5. Test the drain pump: With power restored, run a drain or spin cycle and listen for the pump motor. A silent or grinding pump usually needs professional replacement.
  6. Run a rinse and spin cycle: Once everything is clear, run a short cycle to confirm water drains fully and the C-21 code doesn’t return.

FAQ

Can I ignore the C-21 error and keep washing?
No. The machine will likely stop mid-cycle again, and running it with a blocked drain can cause water to back up or damage the pump.

Will resetting the washer clear C-21 for good?
A reset (unplugging for a minute) clears the error code temporarily, but it will return if the underlying blockage or pump fault isn’t fixed.

Is C-21 the same as a general drain error on other brands?
It’s similar to drain-related codes on other manufacturers’ machines — for comparison, see how the Maytag Washer F1E1 Error Code is diagnosed, as the troubleshooting logic overlaps.