LG Range Error Code C-21

C-21 means the oven cavity temperature exceeded 650°F (343°C) during a standard cooking function such as bake, broil, or convection. This is an overtemperature protection error. The range shuts down heating to prevent damage or a safety hazard. It does not appear during self-clean mode, which is designed to operate at higher temperatures.

Disconnecting power may temporarily clear the code, but it will not fix the underlying problem. If a relay is welded shut, a sensor is faulty, or an element is shorted, the condition that caused the overtemperature event will still be present. The code is likely to return once the oven is used again unless the root cause is repaired.

Repair costs vary depending on which component has failed. An oven temperature sensor typically runs in the range of $20 to $60 for the part. A relay board or control board can cost anywhere from $80 to $250 or more. If you hire a professional technician, expect to add labor costs on top of parts, which can bring the total to $150 to $400 depending on your area and the specific repair needed.

No, you should not continue using the oven while C-21 is active. The code indicates the oven reached a dangerously high temperature, which points to a component failure that has not been resolved. Continued use before diagnosing and repairing the root cause could result in further appliance damage or a fire hazard.

Start by disconnecting power, removing the back cover, and measuring the resistance of the oven temperature sensor at the harness connector. It should read approximately 1080 ohms at room temperature. Next, check the resistance of the bake, broil, and convection heating elements, and inspect the DLB and individual heater relays for signs of failure. Repair or replace whichever component tests outside of its acceptable range.