The "dE" error code on an LG washing machine indicates that the washer door was unable to lock properly. This can be caused by various issues, such as laundry caught between the door and the rubber door gasket, too much laundry in the machine, or a faulty door lock. To resolve the issue, one can try opening and re-closing the door, power off the washer, unplug it from the power outlet or flip the circuit breaker to turn the unit off, press and hold the START/PAUSE button for 5 seconds, plug the washer back in or flip the circuit breaker back on, and try again. If the error code persists, service will be required.