The 40E error on your Samsung Washer means the main control board has lost communication with a sub-component, usually the door lock assembly or the sub PCB. Most of the time this clears up after a power cycle and a check of the wiring connections behind the control panel.

Error code 40E
Meaning Communication failure between the main control board and the door lock switch or sub PCB
Severity Medium — the washer will not start or complete a cycle until resolved
Time to fix 10–40 minutes
Tools needed Phillips screwdriver, multimeter (optional)

What the 40E error means

The 40E code shows up when the washer’s main PCB sends a signal to another part of the system — most often the door lock switch — and doesn’t get a reply back within the expected time. This is a communication fault rather than proof that a part is dead, so it’s worth ruling out loose connections and power glitches before replacing anything.

Because the door lock and control board work together to confirm the door is sealed before a cycle starts, any break in that signal path stops the machine dead. It’s a similar idea to how a Samsung Washer LE Error Code: Causes and Fixes flags a lock-related problem, though the underlying cause on 40E is usually wiring or the board itself.

Common causes

  • Loose or corroded wiring connector between the main PCB and the door lock assembly
  • A faulty door lock switch that isn’t sending a return signal
  • A temporary glitch in the main control board after a power surge or brownout
  • Moisture or condensation inside the control panel housing
  • A failing sub PCB (on models that use one) that can’t relay signals correctly
  • Damaged wiring harness from wear, pinching, or rodent damage

How to fix the 40E error

  1. Power cycle the washer: Unplug it for 2–3 minutes (or switch off the breaker), then plug it back in and run a short cycle to see if the code clears.
  2. Check the door and door lock: Open and close the door firmly to make sure it’s latching properly, then start a cycle. A door that isn’t sealing can trigger the same fault as a wiring issue.
  3. Inspect wiring behind the control panel: With the power off, remove the top or control panel cover and check the connector between the main board and the door lock switch for looseness, corrosion, or damage.
  4. Test the door lock switch: Use a multimeter to check continuity on the door lock switch. If it doesn’t read correctly, the switch likely needs replacing.
  5. Inspect the main PCB and sub PCB: Look for burn marks, bulging capacitors, or moisture damage on the boards. Visible damage usually means the board needs replacing.
  6. Call a technician if the fault persists: If wiring and the door lock check out fine, the main control board is the likely culprit and should be tested or swapped by a qualified appliance repair person.

FAQ

Can I still use my washer if it shows 40E?
No. The washer won’t start a wash cycle safely until the communication fault between the board and door lock is resolved.

Is 40E the same as a door lock error?
Not exactly. It’s a communication error that often involves the door lock circuit, but the root cause can also be the wiring or the control board itself, unlike more direct lock faults such as the Samsung Washer LE Error Code: Causes and Fixes.

Will unplugging the washer fix 40E permanently?
Sometimes, if the cause was a temporary power glitch. But if the error returns after a few cycles, there’s likely a wiring or hardware fault that needs checking, similar to persistent issues seen with the Samsung Washer SE Error Code: Causes and Fixes.