Bosch Microwave ER4 Error: Extreme Overheating
What Does Bosch Microwave Error Code Er4 Mean? Error code Er4 is a critical safety alert indicating extreme overheating or potential fire inside the microwave. DO NOT open the door if you see smoke — disconnect power at the breaker immediately. Immediate Action Disconnect power. Keep the door closed. Wait 30 minutes. Open a window. […]
Quick Assessment
Answer to continue safely
Is it safe to keep using?
No. DO NOT use the microwave. Er4 is a fire safety issue requiring professional inspection.
Can I reset the code?
No. Do not attempt to reset. Professional inspection is mandatory.
When to stop immediately?
Stop if you notice: Immediately — disconnect power, Any smoke or fire.
Symptoms You May Notice
Smoke or burning smell
Visible smoke or a strong burning odor from the microwave cavity or vents.
Microwave shuts down completely
The unit powers off and will not restart.
Possible Causes
Food ignition
Dry food, grease, or packaging caught fire inside the cavity.
DIY PossibleArcing from metal
Metal utensils, foil, or metallic trim caused electrical arcing and extreme heat.
DIY PossibleMagnetron failure
The magnetron is malfunctioning, generating excessive localized heat.
Requires ProfessionalSafe Checks You Can Do
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1
DO NOT open the door
If you see smoke, do NOT open the microwave door. Disconnect power at the breaker immediately.
Opening the door introduces oxygen which can cause a fire to flare. Keep it closed.
-
2
Wait and ventilate
After disconnecting power, wait at least 30 minutes. Open a window for ventilation.
Do not use the microwave again until professionally inspected.
When to Call a Professional
Contact a qualified technician if:
- Cavity shows burn marks
- Waveguide cover damaged
- Magnetron malfunction
Need Professional Help?
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