The short answer
A built-in microwave sits in a housing that was cut and fitted by somebody, and the door has to close against the appliance frame rather than against fresh air. Ranked first on this platform: The door is not closing far enough to satisfy the interlocks. The checks below follow that ranking, and the first of them need no tools and no panel removed.
What you observe
- The panel responds normally, the start button beeps, and nothing happens — A fully responsive appliance that will not run is a permission problem, not a power one.
- The door is definitely shut and properly latched and nothing happens at all — A properly latched door with no response is the interlock rather than the latch.
- It beeps when you press start, or shows a small symbol you do not recognise — A beep is a refusal, and a refusal is usually a lock.
- NEAR MISS — the display is dead as well — No display means no power reaching the control, which makes this a supply question before it is an appliance one.
Causes, most likely first on this platform
- The door is not closing far enough to satisfy the interlocks — A microwave will not run until three separate switches in the door frame agree that the door is shut. It ranks first on this platform because the door on a built-in is the part the installation can interfere with: a trim that has moved or a housing that has settled holds the door a fraction off its frame, and the interlocks read that exactly as an open door.
- A failed interlock switch — The interlock switches are mechanical microswitches with a defined life, and they are operated every time the door is closed. It ranks second here because the tolerances on this platform are tight enough that a fault which would be inaudible on a mass-market machine is obvious on this one.
- The control lock is on — Nearly every microwave has a control lock, usually a long press on a number or a stop key, and it is engaged by accident far more often than deliberately. It ranks third rather than higher: real on this platform, and less common than the causes above it.
Check in this order, and why
- Close the door firmly, with a hand flat against it, and try again — It costs nothing and it is the single most common answer on this appliance. It leads because it tests the top-ranked cause.
- Listen for the small clicks as the door closes and opens — Missing clicks locate the fault at the switch stack. Tests the second-ranked cause.
- Look for a lock indicator on the display and try a long press on the stop key — Ten seconds, and it is free. Tests the third-ranked cause.
What an owner can safely check
- Push the door firmly shut and press start; then open and close it a few times and try again — A latch that engages on the third attempt has told you what is wrong with it.
About 10 min
- Hold the stop or cancel key for several seconds to clear a control lock — Check the door of the appliance for a printed instruction — most carry one.
About 5 min
- STOP here — the remaining causes are diagnosed with a meter, not by eye — Record which of the checks above changed anything. That record is worth more to the visit than another attempt.
Before you touch anything inside
Safety
Do not remove the cabinet of a microwave. The high-voltage capacitor inside can hold a lethal charge long after the appliance is unplugged, and discharging it safely is a trained job with the right tool.
When to call a technician
Call once the door, the latch and the supply have all been eliminated, because what is left is behind the cabinet and behind the cabinet is not owner territory on this appliance.
Nearest pages of this class
What this page does not cover
This page is written for the Miele microwave as a class, not for one family or one model line. Where a family- or model-specific page exists for your unit, that page is the more specific answer and the one to read first. Deliberately not here: part numbers, wiring colours and disassembly order, which differ by family.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
