F99
LG Control Lock or Software Fault

LG oven displays F99 and may not respond to controls or may lock up.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Stuck keypad, Firmware glitch in control board, Electrical noise or surge

How to Fix / Troubleshooting

Safety first: If the oven is heating uncontrollably, turn off the breaker immediately.

  • Control lock: Verify that the control lock feature is not engaged. On many LG models, press and hold the designated lock key (often "Lock" or a key with a padlock icon) for 3–5 seconds to toggle.
  • Power cycle: Turn the breaker OFF for 5–10 minutes, then ON. This can clear software faults.
  • Check keypad: Press each button to ensure none are stuck or unresponsive. If some keys do not work, the touchpad may be failing.
  • Replace control assembly: If F99 persists and the keypad appears functional, replace the control board or complete control panel assembly as specified for your model.
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Repair Difficulty

Medium 3/5

Required Part

Touchpad / Control Panel Assembly
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