How to Fix an LG Oven F9 Error Code

June 3, 2024
Oven Repair

When the F9 error code displays on an LG oven, it means that the appliance has failed to reach 150 degrees Fahrenheit after preheating for five minutes. This error has several potential causes, which we will run through in this guide and offer advice on fixing them.

Since a temperature of 150℉ or less is insufficient to cook food properly, you should avoid using the oven and make alternative cooking plans until the error is fixed. However, you can sometimes fix this error code with a quick reset, so let’s try that first.

Resetting your oven

LG recommends first resetting your oven if you experience the F9 error code. That’s because residual static electricity can sometimes cause the appliance’s electronic devices and control board to behave erratically and inadvertently generate the F9 error code.

Performing a hard reset can clear the error when this is the case. Here’s how to do it:

  1. Unplug your LG oven or switch it off at the circuit breaker.
  2. Wait for 3 to 5 minutes while the power is shut off.
  3. Plug it back in or switch it back on at the circuit breaker.
  4. Attempt to run the oven; if the error code persists, move on to the next troubleshooting tip.

Faulty relay board

The relay board controls the power to the heating elements and other oven components. It helps to ensure the right temperature is maintained by turning the heating elements on and off. If the relay board becomes faulty, the oven may not heat up properly, resulting in the F9 error code on your gas or electric LG oven.

To resolve this issue, inspect the relay board for damage or test it with a multimeter. If it is defective, it will need replacing. Here’s how to check and test the relay board:

  1. Unplug or power off the oven at the circuit breaker and ensure it has cooled down completely for safety.
  2. Pull the oven away from the wall and remove the back panel to access the relay board. For gas ovens, it’s usually in the top right, and for electric ovens, it’s in the bottom right. It looks like a circuit board.
  3. Before removing the old relay board, take a photo of how all the wires are connected to help with the installation of the new one.
  4. Remove the relay board by disconnecting the wires and removing any fasteners or screws.
  5. Then, inspect the relay board for signs of physical damage, such as burnt areas, and test it with a multimeter for continuity.
  6. If it doesn’t have continuity or is damaged, order a replacement relay board.
  7. Install the new relay board in its place, using your photo to ensure you connect all the wires correctly.
  8. Reassemble your oven, turn the power back on, and run the oven to see if the F9 error code is gone.

Faulty igniter

If you have a gas LG oven, a faulty igniter is a common cause of the F9 error code. That’s because a faulty igniter can cause the oven to take longer than usual to heat up or not heat at all, resulting in the F9 error. The igniter is the component that ignites the gas, creating a flame.

Here’s how to check and replace an igniter:

  1. Locate the igniter; it’s usually located at the back of the floor of the oven cavity, near the burner.
  2. Run the oven, and observe whether the igniter glows red-hot within a few seconds and whether a flame ignites.
  3. If the igniter doesn’t glow red or a flame isn’t produced, the igniter is likely faulty and will need replacing.
  4. Disconnect the power supply to the oven and shut off the gas supply. Then, order a replacement.
  5. Remove the oven racks and the bottom panel of the oven cavity to access the igniter. You will need a screwdriver.
  6. Disconnect any wires attached to the igniter and remove any screws securing it. Then, remove the old igniter.
  7. Install the new igniter, ensuring it is positioned correctly, the wires are connected right, and it’s secured with screws.
  8. Put the bottom panel back in, restore the power and gas supply, and run the oven to see if it’s now working properly.

Faulty thermostat

The thermostat regulates the temperature of the oven. It senses the temperature inside the oven cavity and activates or deactivates the heating elements accordingly. If faulty, your oven may not heat properly, leading to the F9 error.

Here’s how to inspect and replace the thermostat:

  1. Disconnect the power supply to the oven.
  2. Remove the back panel of the oven and remove the rack from the cavity.
  3. Locate the thermostat; it’s usually near the back of the oven cavity, connected to the heating element or control board.
  4. Take a picture of how the wires are connected to the thermostat. Then, disconnect the wires and unclip or unscrew the thermostat from its mounting.
  5. Inspect the thermostat for visible signs of damage and test it for continuity with a multimeter.
  6. If damaged or has no continuity, order a new replacement part.
  7. Fit the new thermostat in place, making sure the wires are connected right and all the mounting screws or clips are fastened.
  8. Reassemble the oven, reconnect power, and run it to see if the F9 error has been resolved.

Final words

The issues we’ve outlined above are the most likely causes of the F9 error code on an LG oven. Hopefully, we were able to solve this issue; however, if your LG oven is still displaying this code, we suggest reaching out to your nearest appliance repair service to have your oven thoroughly inspected.


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