Microwave won’t turn on: causes, part cost
Prices checked 2026-08-28
A microwave won't turn on is most often a power supply or outlet fault problem - about 26% of reported jobs. Here is how to confirm it, what the part costs, and when to stop.
A microwave is a magnetron, a high-voltage circuit and a door interlock – the last one being the part that protects you. Most faults are either the door switch or the high-voltage side.
Microwave won't turn on is one of the most common repair searches there is. A unit that will not start is a power or start-circuit problem. Power faults are the cheapest to find; start-circuit faults are the most common part failures.
Before you call anyone: 30-second checks
- Confirm power at the outlet or breaker – the single most common "won't start" cause.
- Check the door, lid or safety interlock – many units refuse to start with a switch open.
- Listen for a click or hum: a hum with no start points at the start relay or capacitor.
The likely causes, ranked
Power supply or outlet fault
About 26% of microwave won't turn on jobs come back to this cause. This is a component-level failure – the part itself has worn out or failed, which is why it sits on the ranked list rather than the free-check list.
How to confirm it: It is worth confirming with a multimeter or a visual check before ordering the part, and worth asking the shop if the part is returnable.
Typical fix: usually free. A capable DIYer can usually handle this one.
Tripped breaker, fuse or GFCI
About 24% of microwave won't turn on jobs come back to this cause. A tripped breaker, GFCI or reset button is the electrical system protecting the circuit – and the cheapest "fault" on the list.
How to confirm it: Check the panel and any GFCI outlets on the circuit; if the breaker trips again immediately, the fault is in the unit or the wiring, not the breaker.
Typical fix: usually free. A capable DIYer can usually handle this one.
Door or lid interlock switch
About 19% of microwave won't turn on jobs come back to this cause. Switches and interlocks tell the unit it is safe to run, and a stuck or failed switch can stop a unit dead or leave it running when it should not.
How to confirm it: A unit that will not start, or starts only when the door is held, points at the interlock switch – a cheap, common part.
Typical fix: $40. A capable DIYer can usually handle this one. You would be looking for a interlock switch.
Failed control board or start relay
About 18% of microwave won't turn on jobs come back to this cause. A motor, fan or pump with its drive components is a wear item – belts stretch, bearings dry out, capacitors lose their charge and relays stick.
How to confirm it: Listen for the motor: a hum with no movement points at a capacitor or belt; a grinding or squeal points at a bearing. Each has a different price tag.
Typical fix: $180. This one is best left to a professional. You would be looking for a control board.
When to stop and call a pro
If it hums but will not start, the capacitor or start relay is the usual part – both are under $40 and easy to swap with the unit unplugged.
How to keep it from coming back
Surges kill start components. A basic surge protector on the circuit is cheap insurance for anything with a motor.
Bottom line: Microwave won't turn on is worth diagnosing before you call anyone – the free checks above catch a surprising share of cases, and the ranked list tells you what the part should cost if it is not one of them. Run the figures through the repair-or-replace test on this page before you authorise any work, and never pay for a diagnosis without getting the part name and the price in writing first.
Likely causes, most common first
| Likely cause | How often | Typical fix | Who does it |
|---|---|---|---|
| Failed door interlock switchinterlock switch | 34% | $50 | DIY-able |
| Failed magnetronmagnetron | 30% | $150 | Pro job |
| Failed high-voltage diode or capacitorhigh-voltage diode | 22% | $60 | Pro job |
| Bad control board or touchpadcontrol board | 14% | $160 | Pro job |
Frequencies are the share of reported jobs attributed to each cause across repair-platform and forum data - a starting point for diagnosis, not a certainty.
What this should cost to put right
Across the causes listed above the repair runs $0 to $180. A quote far above the top of that range is usually a diagnosis of convenience - get a second opinion before you authorise it.
Repair it, or replace the unit?
This is the number people get wrong most often, and it costs them the most. Run the quote through the test - it uses the mid-point cost of the fix above against a new unit and the years this one has left.
REPAIR IT
The repair is 10% of a new unit and the appliance has roughly 4 year(s) of expected life left. Fixing it is the economical call. A new unit would save about $45/year in running costs, so keep repairing until that pays back in under 5 years.
Decision rule: repair when the fix costs under 50% of a replacement and the unit is under 70% through its expected life.
Other microwave symptoms
Common questions
Is it dangerous if my microwave has a "won't turn on" problem?
Usually not immediately - none of the likely causes on this page involve gas, fuel or a mains electrical fault. The two cautions that apply everywhere: keep water away from any electrical point, and if you ever smell gas or burning, stop diagnosing and call a professional.
How much does it cost to fix a microwave with a "won't turn on" problem?
Most fixes for this run $0 to $180. The most common cause, power supply or outlet fault, runs about nothing - it is a free check to put right, and the part you would be looking for is not usually sold separately. Get the diagnosis in writing before authorising anything above the top of the range.
Why does my microwave have a "won't turn on" problem?
In about 26% of reported cases it is a power supply or outlet fault. It is the first thing to check because it is the most common - and usually the cheapest. If that checks out clean, work down the ranked list on this page before paying for a diagnosis.
Should I repair or replace my microwave?
Repair it when the fix costs under half of a replacement and the unit is under 35% through its roughly 9-year expected life. Past that point a repair is usually a deposit on the next failure - run the test on this page with your actual quote before you decide.
How this figure was built
Reviewed 2026-08-28 · quarterly.
- Bureau of Labor Statistics, Occupational Employment and Wage Statistics - construction and repair trades
- EPA Energy Guide appliance ratings
- North American Electrical Metrics / manufacturer parts catalogues
National averages. Local labour can run 20-40% above or below these figures; the calculators apply a metro factor on top.
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