Microwave Oven Troubleshooting


In most homes, the microwave is a jack of all trades. The gadget functions as a coffee maker, defroster, grilling oven, and sanitizing machine. You can de-crystallize, bake, reheat, roast, proof yeast, and do a dozen other functions. Remember that the capabilities depend on the model. When the machine stalls, your home is incomplete so, several microwave oven troubleshooting hints will come in handy.

You can resolve the issues without the need to call your technician. But not all times! At some point, you may have to call an expert to resolve complex problems in your oven. Microwave troubleshooting issues include the oven not heating, a rattling gadget, and sparking, among others. Learn here why your microwave is not shutting off. Let’s also see how to resolve these common errors.

1. Microwave Not Heating (4 Causes And Fixes!)

A new microwave will rarely develop heating issues. All its components are charged up, so the unit functions at the expected timelines. If your oven is barely a month old but develops heating issues, the first thing will be to call the manufacturer. That way, you do not meddle with the warranty contract.

If you bought from reliable sources, all new appliances have a manufacturer’s guarantee. The contract allows for a ship back if the gadget is faulty. For intact warranties, expect free repairs or replacement. So, take note of the guarantee, as some companies offer you the service for up to one year. 

After months or years of usage, your microwave’s performance wane. One of the first signs will be slow heating or not heating. There are several things you can check to fix this snag. Follow them in this order; 

1.      Power Outlet

If you discover your microwave oven is not heating food, the issue could be a faulty power outlet, plug, or wiring. This microwave oven troubleshooting error occurs when there is low voltage in your main power supply. If you have no technical knowledge to test your power voltage, try to plug your appliance into another socket. There will be a change if the flow of current is sufficient. Also, high-power appliances like refrigerators and washers will not function at low voltage.


If you notice a low voltage in your home, seek another cooking alternative as you wait for power to stabilize. An electrician can help determine other issues, such as your device’s wiring, door switch, diode, and other crucial electrical functions in your oven. 

2.      Door Switch

To latch your door, you must have a perfect door switch. The oven design is such that it cannot operate when the door is not latching. When you close the door, it should not leave any space. Also, it should fit and not be loose at all.  


Begin by closing your microwave door so as not to make unnecessary repairs. Next, inspect for a faulty door or switch, as it will not let your oven microwave your food correctly. It could be that the switch broke down or it does not have continuity. Also, the sensor could be faulty. The experts know how best to deal with such a situation. 

If you recently replaced your microwave door or switch and are experiencing heating issues, reinspect the door. It may be a wrong fit, so check the edges or any signs of wear and brace yourself for a replacement.

3.      Diode/Magnetron

The diode charges the magnetron. The latter is the feature that radiates to cooking your food. The turntable will spin in vain if the two functions are not working. Your food will remain cold. What to do? Check below


These two components are complex and require technical knowledge to handle. Also, both are dear to replace. A damaged diode and magnetron replacement can blow off enough dollars to buy another gadget. Make an informed move!

4.      Capacitor 

The capacitor is a high-voltage organ in your microwave. It works alongside the diode (a high-voltage unit) to supply a high-capacity power output. It is this power that charges the magnetron to cook your food. A failed capacitor means a weak diode and a non-functional magnetron.


You can have a capacitor replacement. Experts do the work perfectly and get your oven heating super quickly. It is essential to leave a faulty capacitor to an electrician as it stores dangerous voltage even after you unplug the oven from the wall socket.

2. Microwave Not Shutting Off (4 Causes And Fixes!)

Some microwaves have experienced a continuous turntable rotation even after the cooking time is over. Unless you open the door, the oven doesn’t stop. Whereas it could mean that the oven’s stop control isn’t functioning, several other causes exist. Also, an oven that spins even when the door is open is a scare. Before you figure out your next move, take a video of the rare happenings to share with your tech guy. 

So, if your microwave oven is not shutting off, here are the possible causes of the error;

Control Panel

The control panel is on the face of your microwave oven. Usually, it comes on the left-hand side of the machine. The positioning is deliberate for smooth operations. Microwave oven control panes are the easiest to operate as they have an easy UI. Extended usage and defects can cause your machine’s control panel to stall. The buttons will get stuck and stay pressed damaged. In such a case, your oven can rotate continuously because the sensors are broken. 


Conduct a physical test to determine your microwave oven troubleshooting error. That includes a check if any buttons are working. You can press all the buttons, including the stop/start button. If any of the controls can’t respond, talk to your tech. 

Door Switch

A microwave oven whose door doesn’t shut off may signify an underlying issue with the door switch. The control enables you to close and engage the door. The unit does not sense an open, loose, or closed door if the sensor is not working. There is no breakdown in the relay of information to stop when cooking time is over. 


It is possible to replace a door switch. Ask your tech or dealer to check your gadget.

Control Board

The control board is in the innermost compartment of the machine. Also, it is the centerpiece of your oven’s operation. It regulates the control panel, switches, and other functions. If your gadget’s defective control board is, the microwave may not shut off at the required time. 

Another crucial part of the control board is the relay unit. This one is in charge of controlling the magnetron’s performance, which includes turning the on and off the feature. A defective relay control board may sometimes interfere with your device’s turning on and off function. 


Observing error codes on display is the easiest way to check if your microwave is experiencing issues. For instance, find out in your oven user’s manual if you get a Door Error or any other code. Try opening and closing the door to see if the problem clears away.

Also, a hard reset helps to clear occasional bugs in most appliances. Call a home appliances expert if you need help understanding the issue with your oven. They can help you to replace or repair a faulty control board.


As detailed earlier, the diode supplies save DC power to the magnetron. The latter is the organ that emits heat waves to cook your food. A defective diode can cause your microwave not to shut off, among other malfunctions.


Fixing a microwave diode is not possible. You can replace it and resolve most microwave issues, including shutting off and failing the heating system. Before engaging an expert, you can test your oven’s diode with an ammeter. That is if you are comfortable with the procedure. Beware that a microwave is a high-voltage appliance that can turn lethal. Read the gadget’s manual before making such moves.

3. Microwave Oven Sparking (4Causes And Fixes!)

Your microwave oven is experiencing sparking due to a worn-out rack, metal in the cooking chamber, a damaged waveguide, a defective diode, and a faulty magnetron. 

I will tell you more about the four causes of sparking in microwaves and how to fix them.

Worn Out Racks

Indeed, microwaves are not metal-friendly, yet they come with metallic components such as racks. Though the racks are metallic, they have a coating to prevent metal contact. But the plastic surface can wear off with time. The exposed metal parts get to touch the microwave’s surface, react, and cause a spark. Microwave oven sparking, also arcing, is hazardous. Besides blowing some crucial parts, arcing can cause fire explosions and injuries. So, you must fix the flickering from your microwave.


The first step to clear this microwave oven troubleshooting issue will be to unplug and then remove the metal rack. Inspect if some metallic parts are contacting the oven’s surface. If so, replace the worn-out rack with a new one.  

Faulty Waveguide Cover

Waveguides distribute electromagnetic energy from the magnetron to cook your dish. In all models, the cover features a small square panel on the interior surface of the cooking compartment. Depending on the mode, it can be on the left or right side. Mostly, users forget to wipe the waveguide cover, so dirt accumulates. When the waves burn your food, they also burn the dirt, which causes sparking/arcing. 

A worn-out waveguide cover will also spark. Over time, the sparking causes irreversible damage to the waveguide. Note that you cannot replace a waveguide. If the damage extends from the cover to the unit, your microwave becomes useless. You will have to purchase another unit.


A clean waveguide cover does not spark. Regularly clean your microwave’s interior, including this crucial cover. It protects the waveguide itself. Another measure will be to learn more about arcing in microwaves and how to prevent the issue. For instance, you can teach new members of your family not to use a metallic object in the oven. Also, replace the worn-out waveguide panel to prevent sparking and damage. If you are unsure how to replace the waveguide cover, ask your tech to do it.  

Faulty Magnetron Or Diode

Both the magnetron and diode work together. If any of them misbehaves, it can bring several microwave oven troubleshooting problems. The diode that feeds the magnetron is high-voltage power bank that enables the latter to cook your dish. A fault in any of the two units will cause your microwave to flicker.

Also, a burnt smell is the surest way to determine that your microwave oven is sparking due to a diode error. The unit could be worn out or has a short circuit. Also, when it splits into two, sparking occurs. Although most technicians say that the magnetron rarely causes sparking, it is reasonable to inspect and replace it if worn out. A new one will increase microwave frequencies to heat your food effectively.


A tech will unscrew your microwave’s access panel and reach out to the diode. After checking the continuity, the team will advise whether to replace the diode or magnetron. Forget handling the diode, as it is a high-voltage unit that works with the capacitor. The latter contains dangerous electric power and can injure you.  

Metals In The Cooking Chamber

As I detailed, metals cause sparking in microwave ovens when they come into contact with their surface. These can include tinfoil, aluminum foil, steel wool fragments, cutlery, metallic plates, etc.


Adhere to the rule that forbids you not to use metal ware in your oven. Most manufacturers indicate the instructions in your gadget’s user manual. Avoid spoons, knives, foils, and steel scrubbers in the oven. You can use a cloth scrubber to clean your unit.

4. Microwave Oven Rattling (4 Causes and Fixes!)

A trembling gadget on a kitchen countertop is an uncomfortable sight. You aren’t sure if it will dismantle or dropdown. Such an occurrence will make you suspend all your cooking. If your microwave oven rattles, the problem could be a defective magnetron, fan, diode, turntable, and stirred motors. So, you need several microwave oven troubleshooting hints.

 I will help you to define these issues.

Defective Magnetron

In normal operations, the magnetron emits high-frequency electromagnetic waves to cook your meals. The feature is audible enough even in a low setting. This sound should be a hum, so an irritating pitch higher rattling noise from your microwave’s magnetron indicates defects. Primarily, a noisy magnetron signifies old age or heavy usage.

A faulty magnetron requires an exchange. The first step is to run your oven at the lowest setting to determine if the noise reduces. If not, call your repair person to do the exchange. 

Defective Diode 

The diode is a high-voltage feature that gets power from the capacitor and supplies it to the magnetron. Its intermediary purpose is to convert the essential DC power from the capacitor’s AC. Both the diode and magnetron hum, but not excessively loud. You can test for a faulty diode if you ascertain that the magnetron is sound. Most of these processes require an expert. They will test for continuity and replace the faulty unit for you. 

Defective Fan

Generally, a fan will make some commotions when rotating. It only becomes a bother if there is a rattle. That indicates a more complex issue, such as a motor issue or debris that requires removal. A dislodged wave blade or broken base can also rattle, so you must figure out the exact issue.

The buzzing noise will come from the rear of your oven. You may need to remove several parts to reach this critical microwave component. Of course, this requires more caution, especially when handling the high-voltage capacitor.

Before beginning any microwave oven troubleshooting process:

  • Ensure that you understand the task ahead.
  • Unplug your gadget to discharge the capacitor.
  • Remove all the parts that block your access to the cooling fan.
  • Once you access the unit, examine the rotation process.

The above process will help you to figure out if it is a case of debris or broken fan parts. Dislodged components, such as the blade and base, will require tightening or replacement.

Defective Motors

A rattle, a click, or a grind indicates faults. It could be because of ineffective placement where you can access the unit and adjust. You may have to call your repair person for testing and replacement if the motor has an issue.

The stirred motor is quite different from the turntable motor. Its purpose is to sidetrack your oven’s microwave energy in the cooking process. In so doing, your meal cooks evenly. If your oven’s stirred motor struggles to deflect microwaves, it will make rattling sounds. Old age and overworking can cause this issue, so you may need someone to replace the unit.  

Final Thoughts

At some point, you may experience some microwave oven troubleshooting problems. That is typical with appliances. You shouldn’t grumble and pack your oven in the store. Issues such as rattling, sparking, not shutting off, and failure to heat or cook food are fixable. Some will require the help of an expert.

Do not hesitate to consult your technician for more pronounced issues. That way, you will not experience further damage. Also, you stay safe from high-voltage components such as the diode and capacitor. Good luck.

By Shawn Roberts

Shawn Roberts is a renown culinary enthusiast with a deep love for food and cooking. He has decades of experience in the kitchen. In his career, Shawn Roberts shares his expertise, recipes, and insights to inspire and guide you on your own culinary journey. Together with his team of kitchen décor experts, you can make your cooking space a little heaven. Get ready to explore a world of flavors and creativity with Shawn Roberts