The door latch on a dishwasher serves two purposes: it physically holds the door closed during operation, and it contains a switch that signals the control board the door is secured before allowing a cycle to start. When the latch fails, the dishwasher won't respond to the start button — the control board treats it as an open door.
Latch failures are usually visible: the door doesn't click when you close it, or it springs open slightly during the cycle. Sometimes the physical latch is fine but the internal switch has failed — the door feels secure but the switch no longer sends the closed signal.
Door latch assemblies are inexpensive components. Our technician tests the switch for continuity and replaces the latch assembly if needed — a straightforward repair completed at the front of the machine without major disassembly.