KitchenAid Cooktop Error Code F-21

F-21 is a supply power frequency error on a KitchenAid cooktop. It means the power control board has detected a fault in its ability to read or process the incoming AC line frequency. This is a Type 2 fault, so all burners connected to that power control board are affected. The fault originates within the power control board itself.

Disconnecting power and restoring it may temporarily clear the display, but if the power control board has failed, the F-21 code will return once the cooktop attempts to operate. A reset does not address the underlying board fault. Replacement of the power control board is required for a lasting repair.

The cost depends on the price of the replacement power control board and whether you hire a technician. Parts alone typically range from around $80 to $250 or more depending on the specific model. If you hire a professional, labor costs can add $100 to $200 or more to the total, bringing the full repair range to roughly $180 to $450 or higher.

The repair requires disconnecting the cooktop from power and replacing the power control board. A knowledgeable DIYer comfortable working with appliance electronics can perform this repair, but it is critical to ensure power is fully disconnected before beginning. If you are not confident working inside the appliance, a qualified appliance technician is the safer choice.

No. When F-21 is active, all burners on the affected power control board are disabled or may behave unpredictably. Continued use is not recommended. The cooktop should remain powered off until the power control board has been replaced and the fault is resolved.