What causes a washing machine door to lock?

Residential washing machines automatically engage electronic door or lid locks during operation as a mandatory safety feature required by federal regulations to prevent users from opening the spinning drum during high-speed rotation. The locking mechanism is typically controlled by an electronic signal sent from the main control board to an internal thermal wax motor or solenoid, which drives a physical locking pin into the door strike. If the washing machine locks and refuses to open after a cycle finishes, common causes include a frozen control board, residual standing water remaining inside the drum, or a burnt-out wax motor that fails to cool and retract. You can troubleshoot lock states easily. You can verify that your corrective action is successful when performing a power reset releases the interlock.