The short answer
If a Bosch microwave trips the breaker, sparks inside, or smells of burning, unplug it and stop using it. The only owner checks are the circuit it shares, the cord and plug, and whether something metal or a damaged cover is causing arcing inside the cavity. Nothing inside the case is owner work.
What you observe
- The breaker trips when the oven starts — A load or a fault on a circuit that cannot carry it.
- Arcing or sparks inside the cavity — Metal in the cavity, or a damaged cover over the waveguide opening.
- A burning or hot-plastic smell — Stop immediately. Unplug and do not run it again.
- The plug or cord is warm to the touch — A connection problem outside the oven, and still a reason to stop.
- NEAR MISS - a strong smell the first few times a new oven runs — Manufacturing residues burning off. It fades within a few uses.
Causes, most likely first on this brand
- A shared circuit that cannot carry the load — First for tripping. A microwave draws heavily, and on a kitchen circuit shared with a kettle, a toaster or a disposer the breaker is doing exactly its job.
- Metal in the cavity or a damaged waveguide cover — First for arcing. Foil, a metal-trimmed dish or a burnt cover over the waveguide opening will all spark, and the cover is the one that keeps sparking after you remove the dish.
- A damaged cord, plug or outlet — Third. Over-range ovens sit above a heat source and their cords are often routed tightly, and a damaged cord trips protection or runs warm.
- Food residue burning in the cavity — Fourth, and the usual explanation for a smell without a trip. Splashes on the roof of the cavity char and smoke.
- An internal fault in the oven — Last, and not an owner matter at any level. Repeated trips with nothing else on the circuit mean unplug it and call.
Check in this order, and why
- Unplug the oven first if it has sparked or smelled hot — That is a stop, not a step, and everything else waits.
- Note what else is on the same circuit — A trip that happens only when the kettle is on is a circuit problem.
- Look at the cover over the waveguide opening in the cavity — Burnt, holed or missing, it will keep arcing whatever you cook.
- Inspect the cord and plug along their whole length — Damage, heat marks or a loose plug are visible without tools.
What an owner can safely check
- Unplug the oven and let it stand — Do this first if there has been any arcing, smoke or smell. Do not open the case at any point.
About 10 min
- Run the oven alone on its circuit — With nothing else drawing on the same breaker, try a short heat with a cup of water.
About 10 min
- Clean the cavity thoroughly — Warm water and a soft cloth on the roof, walls and floor; remove charred splashes that smoke.
Tools: cloth, warm waterAbout 20 min
- Inspect the waveguide cover — If it is burnt, holed or missing, stop using the oven until it has been replaced by a technician.
About 10 min
- STOP HERE for anything inside the case — There are no owner-serviceable parts behind the panels.
Before you open anything
Safety
A microwave oven contains a high-voltage capacitor that can hold a lethal charge long after the oven is unplugged. Never remove the case, never test anything inside it, and never treat a microwave as you would another appliance. Unplug and stop using the oven for any arcing, smoke, burning smell, damaged cord, or trip that repeats with nothing else on the circuit. Reset a tripped breaker once at most, and never run the oven empty.
When to call a technician
Call whenever the oven trips its breaker with nothing else on the circuit, whenever there has been arcing that continues after the cavity is clean and empty, and for any burning smell or smoke. Call an electrician rather than an appliance technician if the trip happens only with other appliances running, because that is the circuit rather than the oven. In every case, unplug the oven first.
Nearest pages of this class
What this page does not cover
This page covers the Bosch built-in and over-range microwave ovens as a class rather than one model family, and a family-specific page is linked below where one exists. Deliberately absent: power ratings, circuit requirements, component part identifiers and any internal test procedure - a microwave's internals are not an owner subject at any level of detail, whatever the family.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
