Could not find any info on the given model number, seems to be short several digits. Kenmore number are usually 3 digits, a period and then 8 digits.
Please check it.

Could be a dead key on the keyboard.
Check the other keys to make sure they all work. The keys often use a common line for about 3 keys.

Here are your parts
Replacement parts for KENMORE 66513744K601 | AppliancePartsPros.com

See the attachment for the tech sheets.

Could be the control panel (keypad) or the control board.
Only way to tell is to check the keys as shown in the tech sheet using a meter.

If you do see other keys that use the same ribbon cable tracks (wires) then it may just be a bad connection so I would try the following.

Connector Cleaning / Checking
Unplug the unit
Open it up
Remove the ribbon cable from the keypad to the control board at the control board.
Clean the edge connector.
If it is the type where there is not a connector just the insulation is removed, it can be cleaned with a pencil eraser. Do not use an ink eraser as it is too abrasive.
Check the tracks in the ribbon cable for hairline cracks. A magnifying glass helps here.
Would not hurt to clean the connector on the board. Use electronics contact cleaner or isopropyl alcohol and a tooth brush. Be gentle and do not reconnect till all the solvent evaporates.
Reconnect everything and give it a try.