You've seen the YouTube video — the "automotive microwave trick," the "microwave key reset," the "put your car key in the microwave for 10 seconds" hack. Someone puts a car key in a microwave for a few seconds, the chip "resets," and the key magically works again. Tempting, isn't it? Especially if it's 11pm and your only key has just died.
Don't do it. It's a myth — and a dangerous one. Here's exactly why microwaving a car key doesn't work, what it actually does, and the right way to fix a key that has stopped working.
Where the Myth Started
A few years ago, a viral video showed someone putting a car key in a microwave "to reset the transponder chip." The video got millions of views, and the idea stuck: microwave = reset = free fix. Unfortunately, the original video was either a hoax, a misunderstanding, or someone who got lucky for a moment before the key stopped working altogether. The myth has stuck around because it sounds plausible — microwaves heat things, electronics can "reset" with a power cycle, why not?
Here's the problem: transponder chips don't work like that.
What a Transponder Chip Actually Does
Your car key has a tiny passive transponder chip sealed inside the plastic head. It has no battery. When you insert the key into the ignition, the car's immobiliser sends a low-frequency radio signal to the chip. The chip powers up, transmits a unique code back, and if the code matches what's stored in the car, the engine starts.
This is why copying a key isn't enough — you also have to programme the chip to your car's immobiliser. The chip doesn't "reset" in any meaningful sense. It either has the right code, or it doesn't. There's no stored state that a microwave could clear or restore.
What Actually Happens If You Microwave a Car Key
Let me be very clear about what you're doing if you put a car key in a microwave:
- The transponder chip is destroyed. The microwave's electromagnetic radiation heats the metal in the chip and circuit board. The chip's data is corrupted — permanently. Your key is now a non-functional piece of plastic with a dead circuit board inside.
- The remote fob's circuitry is destroyed. The buttons, the battery contacts, the radio transmitter — all of it. The microwave is many orders of magnitude more powerful than the key fob's normal radio signal. It will fry everything.
- The plastic casing melts or warps. Car key housings are made of ABS plastic. After 5–10 seconds in a microwave, they're deformed, often beyond recognition.
- It's a fire risk. Microwaving metal — which is exactly what is inside a key fob (the circuit board traces, the battery contacts, the chip's antenna coil) — causes arcing, sparks, and in some cases, has started kitchen fires. The key fob battery can also rupture.
- It damages your microwave. Repeated arcing inside a microwave can damage the magnetron (the component that generates the microwaves). A new magnetron costs more than a new car key.
In short: you start with a car key that has a problem, and you end up with no car key, a damaged microwave, and potentially a kitchen fire.
Why Some People Think It "Worked"
There are two reasons this myth has persisted:
- Coincidence. Sometimes a key that has "stopped working" starts working again on its own — usually because the battery had a loose connection, the chip was momentarily not aligned with the reader, or there was environmental interference. If someone microwaves their key in that window, they'll swear the microwave "reset" it. The key was always going to work again.
- The key temporarily heating up. In rare cases, a key that has been exposed to extreme cold (left in a car overnight in winter, for example) will start working once it's warmed up. A microwave will absolutely warm a key up — and so will holding it in your hand for 30 seconds. The microwave adds nothing except destruction.
What to Do Instead — The Real Fixes
Whether your key has actually stopped working or you're just hoping for a free miracle, here are the real things to try, in order:
1. Replace the Remote Fob Battery
If the issue is that the remote buttons (lock/unlock) have stopped working but the car still starts with the key, the problem is almost certainly a dead battery. Most key fobs use a CR2032 or CR2025 coin cell — £2-£3 from any supermarket. See our car key fob troubleshooting guide for step-by-step battery replacement.
2. Try Your Spare Key
If the spare works, you know the car is fine — the issue is with your main key. If the spare also doesn't work, the issue might be with the car's immobiliser system, not the key.
3. Warm the Key Up Naturally
If your key has been exposed to cold (left in the car overnight, dropped in snow), let it warm up gradually. Hold it in your hand for a few minutes, or put it in a pocket close to your body. Don't use a microwave, hairdryer on hot, or any other artificial heat source — those will damage the electronics.
4. Reprogramme the Key
Some older vehicles allow manual reprogramming of the remote (not the transponder — that's dealer-level equipment). The procedure is vehicle-specific. Search "[your car make/model] key fob reprogramming" to see if there's a procedure for your car.
5. Call a Mobile Auto Locksmith
If the above hasn't worked, the transponder has likely lost its programming, the key has an internal fault, or both. A mobile auto locksmith can:
- Diagnose whether the issue is the key, the car, or the environment
- Reprogramme an existing key to your vehicle
- Cut and programme a brand new replacement key on-site
- Recover the key data from your car's immobiliser (for all-keys-lost situations)
This is faster, cheaper, and less destructive than the microwave option. And the key will actually work afterwards.
How Much Does the Real Fix Cost?
| Real Fix | Typical Cost | Microwave Option |
|---|---|---|
| New key fob battery (DIY) | £2-£3 | Destroys the key, costs you £150+ replacement |
| Mobile locksmith diagnose + reprogramme | £60-£100 | Same outcome, plus destroyed microwave and possibly a fire |
| Full replacement key cut + programmed on-site | £120-£250 | About the same as the original YouTube video's cost in damages |
The One-Sentence Answer
No, you cannot microwave a car key to reset it. A microwave will destroy the key, the chip, the fob, and potentially your microwave and your kitchen. The myth is fake. Replace the battery, warm the key up naturally, or call a mobile auto locksmith for the real fix.
Need a Real Fix in East Yorkshire?
If your car key has actually stopped working — or you've already tried the microwave and need a replacement (we get this call) — we can help. We come to you anywhere in Bridlington or East Yorkshire, diagnose the problem, and either reprogramme the existing key or cut a brand new one on-site. Most jobs are done within the hour.
For a full breakdown of what to try before you call a professional, see our key fob troubleshooting guide. And if you're stuck on a budget and wondering what other DIY tricks might work, this article is a good summary of the different key types and how they work.
Need a car key fixed or replaced?
Call Bridlington Keys on 07706 303038 — mobile service across Bridlington and East Yorkshire. Fixed prices, no microwave required, no fire risk.