Is my microwave leakinga plain-English guide
There is a published UK limit and a real test for this, and the door seal is what usually fails it. What there is not, is a way to check it at home.
Take care
Get a qualified appliance engineer to look at your microwave
We do not pass enquiries to a repair firm, so there is no form here. When you book a qualified appliance engineer, tell them the make, the model and the exact code or message on the display, and ask whether they carry parts for this make — that is what turns one visit into a repair rather than a quote.
What this means
This is the worry that brings people to a microwave page rather than a fault, and it deserves a straight answer rather than reassurance. There is a limit, it is written into the standard these appliances are built to in the UK, and it is specific: leakage from a microwave oven must not exceed 5 mW/cm² at any point 50 mm or more from the outside surface. Whirlpool Europe use exactly that figure in their own service instructions, and their instruction when a machine exceeds it is unambiguous — the unit has to be taken out of service until it has been repaired and safety tested.
The test itself is a trade procedure and not a difficult one: a calibrated detector held about 5 cm from the surface and moved slowly around the appliance with a water load inside, paying particular attention to the door, the door glass, the seal and the ventilation openings. What matters for an owner is which part of that usually fails, and the answer is consistent — the door seal and sealing surfaces. Wear, a build-up of baked-on soiling, corrosion, arcing damage, a warped door or damaged hinges are the mechanisms manufacturers name, and it is why their instruction is not to operate an oven whose door does not close firmly against its support, whose trims or seals are damaged, or which shows visible damage or evidence of having been dropped.
Two things you should not do with this. Do not try to check it yourself with a phone app, a mobile phone in the cavity, or a supermarket leakage card — none of those is a measurement, and the phone trick tests the appliance’s ability to block a completely different frequency at a completely different power. And do not assume that because the routine electrical test on your appliance passed, leakage was checked: in the UK it explicitly was not. The IET Code of Practice removed microwave in-service leakage testing at its fourth edition, on the stated ground that it "does not directly relate to ‘electrical safety’". So the test that would find this is a deliberate extra rather than part of the standard check, which is exactly why a visibly damaged door deserves a decision rather than a wait-and-see.
What causes it
| Cause | What is actually happening | How likely |
|---|---|---|
| Door seal worn, soiled or damaged | The part manufacturers single out, and the one their engineers are told to pay particular attention to when testing. | Common |
| Door warped or hinges damaged | A door that no longer closes firmly against its support is a condition manufacturers say means not operating the oven. | Common |
| Arcing damage to the sealing surfaces | Listed by name among the checks before an oven is released, alongside general wear and other damage. | Occasional |
| Damaged door glass or a dropped appliance | Manufacturers say not to operate an oven with broken door glass, and treat evidence of dropping as its own check. | Occasional |
| Cabinet or waveguide disturbed by a previous repair | Connections, waveguides, flanges and gaskets must all be secure, which is why leakage is retested after any such work. | Rare |
Can you fix it yourself?
Stop — this needs an engineer
What it costs to fix
Typical repair cost
£0–£90
Time on site
20 minutes
Nothing to inspect and clean it yourself. A leakage test as part of a visit is typically £60 to £90, and a door seal or a door assembly on top of that varies enormously between a countertop model and a built-in one.
Typical UK prices including parts and labour, updated September 2026. Your quote may differ.
Own this appliance and had this code? . Nothing is published until a person has read it.
Related microwave fault codes
- Microwave completely deadGet it checkedNo display, no light, no fan. On a microwave this is very often a safety system working as designed, and fitting a new fuse is the wrong repair.Related: door interlocks and containment
- Door will not openGet it checkedThe button presses and nothing releases. On a microwave the latch is part of a safety chain, so forcing it is worse than it looks.Related: door interlocks and containment
- Not heating but runningGet it checkedThe light is on, the turntable is going round and the food comes out cold. This is the classic microwave failure and none of it is an owner repair.Related: same brand
- Sparking inside the microwaveGet it checkedBright arcing and a scorched smell. Look at the small panel on the cavity wall before you run it again — a burnt waveguide cover is the usual answer.Related: same brand
- Turntable not turningUsually simple to fixFood heats in patches and the plate sits still. Almost always the coupler, the roller ring or a plate seated wrongly, and mostly fixable in the cavity.Related: same brand
- Ran the microwave emptyGet it checkedRunning a microwave with nothing in it is the one thing an owner can do that reliably damages it, and the service manuals put it in capitals.Related: same brand
Related guides
Common questions
Does the mobile phone test work?
No, and it is worth knowing why rather than just being told. Putting a phone in the cavity and ringing it tests whether the enclosure blocks a mobile signal, which is a different frequency at a tiny fraction of the power. A microwave can pass that and still exceed the leakage limit, and can fail it while being perfectly compliant.
What is the actual limit?
5 mW/cm² measured at 50 mm from the surface of the appliance, which is the figure in the standard microwave ovens are built to in the UK and the same figure Whirlpool use in their own service documentation. Above it, their instruction is that the appliance is taken out of use until repaired and safety tested.
My microwave was PAT tested. Was leakage checked?
Almost certainly not. Microwave in-service leakage testing was removed from the IET Code of Practice at the fourth edition, on the ground that it does not directly relate to electrical safety. Many engineers still offer it, but you have to ask for it as a separate thing.
The door is damaged but it still cooks. Can I keep using it?
The manufacturers answer this one for us, and they answer it as an instruction rather than as advice: do not operate the oven if the door is warped, the hinges are damaged, the trims or seals are damaged, or the door does not close properly. That the appliance still cooks is not the test being applied.
Technical review
Not reviewed by an engineer
No engineer has read this page. Severity follows what the manufacturer publishes, and we would rather tell you that than let a byline imply a sign-off.
Sources and how we verified this
We establish the facts from the sources below and then write the explanation ourselves. We do not copy manufacturer wording and we do not host their manuals.
- Manufacturer technical and service documentation
- Trade body guidance
This page has not been reviewed by an engineer, and we would rather tell you that than imply otherwise. The severity rating follows what the manufacturer publishes: where they say isolate the appliance and call someone, so do we.