The 21C error on your Samsung Washer means the machine’s control board has detected a fault in the drain pump or heater circuit during a wash cycle. This usually stops the cycle partway through and needs checking before you can continue washing.

Error code 21C
Meaning Drain pump or heating circuit fault detected by the control board
Severity Medium — the washer usually won’t complete a cycle until this is resolved
Time to fix 15–40 minutes
Tools needed Multimeter, towels, basic screwdriver set

What the 21C error means

The 21C code appears when the washer’s internal sensors pick up an abnormal reading from either the drain pump circuit or the water heating element. The control board is designed to stop the cycle rather than risk damage or an unsafe wash, so it displays this code and pauses operation.

In most cases this is caused by something blocking the drain system or a loose wiring connection, rather than a major mechanical failure. It’s similar in nature to other Samsung fault codes like the Samsung Washer SE Error Code, where the board flags a circuit it can’t verify is working correctly.

Common causes

  • Drain pump filter blocked with lint, coins, or small debris
  • Kinked or clogged drain hose restricting water flow out of the machine
  • Loose or corroded wiring connector at the pump or heater
  • Faulty drain pump motor that has worn out over time
  • Water heating element failure or a damaged sensor wire
  • Control board fault reading the circuit incorrectly

How to fix the 21C error

  1. Power down and unplug the washer — Always disconnect power before inspecting or touching any internal parts.
  2. Check and clean the drain pump filter — Locate the filter cover (usually bottom front of the machine), remove it carefully over a towel, and clear out any debris.
  3. Inspect the drain hose — Pull the hose free and check for kinks, blockages, or buildup, then reconnect it securely.
  4. Examine wiring connections — With the machine unplugged, check the connectors at the drain pump and heater for looseness or corrosion, and reseat them firmly.
  5. Test the drain pump and heater with a multimeter — If you’re comfortable doing so, check for continuity; a reading of zero or infinite resistance suggests a faulty part needing replacement.
  6. Reset the washer and run a test cycle — Plug it back in, select a short cycle, and watch to see if the 21C code returns. If it does, the pump or heater likely needs professional replacement.

FAQ

Can I keep using the washer after a 21C error?
It’s best not to. Running further cycles with a blocked drain or faulty heater can cause water damage or further electrical faults.

Will clearing the filter always fix 21C?
Not always, but it resolves the issue in many cases since blocked filters are the most common cause of this code.

Is 21C dangerous to ignore?
It’s not an immediate safety risk, but ignoring it can lead to water leaks or a burnt-out heating element, so it’s worth addressing promptly. This is similar to how ignoring codes like the Samsung Washer LE Error Code can lead to bigger repairs later.