Microwave smells of burning or melting plastic (all brands)
⚠️ This needs a qualified professional
This fault involves gas or mains electrical work. Don't attempt a DIY repair — UK law requires gas work to be carried out by a Gas Safe registered engineer. Below is what to check and describe to them, not step-by-step repair instructions.
A burning or melting-plastic smell from a microwave needs to stop you using it immediately — but as with several other appliances on this site, the cause is very often something simple and removable rather than a dangerous internal fault.
What’s safe to check first (with the microwave switched off)
- Check you weren’t using a container that isn’t microwave-safe — some plastics melt or scorch at microwave-safe food temperatures, and this is one of the most common causes of exactly this smell.
- Check for food residue burnt onto the interior walls or the waveguide cover (see our sparking guide), which can produce a burning smell on subsequent uses even after the original incident.
- Check nothing was left running empty or with too little food/liquid inside — microwaving with nothing to absorb the energy can cause the appliance itself to overheat internally.
⚠️ Stop using it if the smell persists
If you’ve ruled out a bad container and cleaned any burnt residue, but the smell continues on a normal, empty-of-debris run, or if you see any sparking alongside it, stop using the microwave and don’t attempt to open the casing yourself. Microwaves store genuinely dangerous electrical charge in an internal capacitor even when unplugged — this needs a qualified appliance engineer, not further DIY testing.
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