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Bosch Oven Not Heating? Here’s Why (+ How To Fix)

Did you know Bosch is the 6th most reliable appliance brand according to Consumer Reports’ 2022 Appliance Brand Reliability Rankings? That’s because of their overall reliable and efficient products, including ovens. However, even the best things can have issues now and then — like your Bosch oven not heating.  

Here is why your Bosch oven is not heating:

  • The oven is in ‘Demo’ mode.
  • The circuit breaker has a lower electrical power.
  • A heating element is damaged.
  • The oven igniter is damaged.
  • The temperature sensor is defective.

Some of these issues have simple causes and can be easily fixed. Others are complex and require the expertise of a professional Bosch servicer. Read on to know which problems you can handle on your own and which ones warrant a call to after-sales service.

The Oven Is in ‘Demo’ Mode

‘Demo’ mode is a sales support feature that allows potential Bosch oven buyers to familiarize themselves with the appliance’s functionality. While on display, a Bosch oven in ‘Demo’ mode is connected by a trained technician to 120V inside a junction box that satisfies the NFPA/NEC Guide to Wire & Box Installations

This means the unit won’t be heating up because a fully operational Bosch oven should be connected to a 240V outlet. If your range is still in ‘Demo’ mode when you first use it, the unit won’t heat up. Therefore, you need to change the settings.

How To Turn Off Bosch Oven ‘Demo’ Mode

To deactivate Bosch oven ‘Demo’ mode and get it to heat:

  1. Select the ‘Settings’ option.
  2. Follow the guide on the display screen to scroll through the menu and choose the ‘Demo Mode’ option.
  3. Change the setting from ‘ON’ to ‘OFF’.
  4. Tap the ‘Enter’ key to save the changes.

Your Bosch oven should now start heating normally — unless it has other issues.

The Circuit Breaker Has a Lower Electrical Power

The circuit breaker (or fuse box) regulates the electrical charge to your Bosch oven before your oven’s control board sends it to the oven’s components. Oven manufacturers always indicate the size of the circuit breaker your appliance should be connected to. 

So, if you connect your oven to a circuit breaker with a lower voltage than indicated for your model, the oven won’t heat up. Also, the oven circuit breaker switch will keep tripping.

How To Resolve Circuit Breaker Low Electrical Power

If you want to be 100% sure your Bosch oven is connected to a correctly sized circuit breaker, you need to have a trained Bosch oven technician install your oven. If your oven is already installed and you suspect breaker size issues, check the amperage (A) indicated on your breaker and the amperage specification on your model’s user or installation manual. 

For example, the Bosch 800 Series-HBL8451UC 30″ single wall oven has a 30A rating. If connected to a circuit breaker with a lower amp rating, the oven won’t heat up. In that case, call the installer or a trained electrician to rectify the installation error. Do not try to resolve this issue on your own, as you could risk further damaging the oven or electrocuting yourself.

A Damaged Heating Element

When you set and start a cooking cycle, the heating element converts electrical energy into heat energy circulated in the oven cavity. If a heating element in the oven is damaged, this doesn’t happen. 

There are several ways to tell if a heating element in your Bosch oven is damaged.

  • The element doesn’t glow red/orange when the oven is turned on.
  • The element has signs of wear (e.g., cracks, blisters, or a break).
  • When tested for continuity with a multimeter, the element doesn’t record any resistance or voltage.

You should have a damaged Bosch oven heating element replaced.

Replacing a Damaged Bosch Oven Heating Element

Bosch recommends that you never attempt to repair a damaged oven heating element yourself. This is because ovens use high-voltage electricity, so you’ll risk an accident if you aren’t able to perform the repair properly. Instead, talk to Bosch Customer service by calling 1-800-944-2904 or contact them on the Bosch Oven & Ranges Support Page.

But if you have training in handling electrical appliances or feel up to the task, here’s how to replace a damaged Bosch oven heating element:

  1. Ensure no power gets to the oven by flipping the circuit breaker switch.
  2. Pull the oven range from the wall.
  3. Unscrew the back panel and place it aside.
  4. Remove the heating element connection wires. Be sure to mark where each wire goes.
  5. Take out the screws holding the heating element from the back.
  6. At the front, open the oven and remove its racks. 
  7. Unfasten the screws holding the bake element. You can also remove the oven door if doing so makes the work easier (though you should be aware that you’ll have to reinstall it afterward).
  8. Pull out the heating element.
  9. Place the new element where the old one was and fasten the holding screws.
  10. Put back the racks and replace the door (if you pulled out the latter). 
  11. Replace the screws at the back of the oven and reconnect the wires. 
  12. Place back the rear cover and screw it on.
  13. Power the oven and test if it now resumes heating.

You may want to check these steps on this how-2-repair.com YouTube video:

A Faulty Oven Igniter

Your Bosch gas oven needs both gas and electricity to function. Although the burners will burn with gas, you need an electrical current to run the igniter.

When your igniter is lit, the gas safety valve senses when the igniter is heated enough and opens the gas to light the burners.

If the igniter is faulty, it won’t build up heat, and the safety valve won’t get the burners going. This is why your oven doesn’t heat. 

You should replace a faulty oven igniter.

How To Replace a Bosch Oven Igniter

To replace a Bosch oven igniter, follow these steps:

  1. Turn off the gas and power to the range.
  2. Remove the rear panel of the oven to access the igniter wire.
  3. Release the igniter wire from the harness.
  4. Remove the oven door. 
  5. Take out the oven racks.
  6. Unscrew the bottom panel inside the oven and remove it.
  7. Remove the screws holding the igniter to the burner and take the igniter out.
  8. Place the new igniter in the position of the old one and screw it to the burner.
  9. Pass the wire of the newly installed igniter to the rear.
  10. Replace the bottom panel, racks, and oven door.
  11. At the back, reconnect the igniter wire to the harness.
  12. Screw the rear panel back to its position.
  13. Turn on power and gas, and check if the oven resumes heating.

A Defective Temperature Sensor

A Bosch oven temperature sensor detects the temperature in the cavity and signals the control board to cycle power to the heating element as required. 

If the temperature sensor malfunctions, it can continuously signal no heat, causing the control board not to cycle the oven to heat. A defective temperature sensor has to be replaced.

How To Replace a Bosch Oven Temperature Sensor

Follow these steps to replace a bad Botch oven temperature sensor:

  1. Turn off the power to the oven and unplug the power cord.
  2. Remove the rear panel by taking out the screws.
  3. Find the sensor wires at the upper right and press the tabs on the wire harness to release the sensor. 
  4. Remove the screws holding the sensor and pull it out of the oven.  
  5. Push the new sensor into the oven and secure it with the screws.
  6. Reconnect the sensor to the wire harness.
  7. Plug the oven and switch on the power. The oven should start heating normally.

Note: Bosch always recommends that the replacement of oven parts be done by an expert. Perform these troubleshooting steps only if you’re absolutely sure you can do them safely.