The link Barbara H. provided covers F21 fault codes, I added the information and explanation of the F24 fault code below.
The model number should be somewhere along the opening of the tub after opening the door. It will start with the number 110.xxxxxxxx
The F24 fault code implies a water temperature sensor error. This can be caused by a loose or bad wire connection at the temperature sensor or at the control board, a faulty temperature sensor or a faulty control board.
The water temperature sensor (key#24) is located at the bottom front area of the tub. See image below.
You will need to remove the lower access panel located below the door in order to access and check the temperature sensor. It can be tested by disconnecting the sensor and checking the resistance with an ohm meter. Compare the reading to chart I added in the image below. If it measures according to the temperature, then the wires and connection at the control board will need to be checked. The control board housing will have the letters "TH2" embossed on it to indicate temperature sensor. Disconnect the two wire temperature sensor connector and test the resistance with the ohm meter. It should measure the same as it did when the resistance was measured directly across the sensor. If it measures according to the information I added in the image, then the control board is likely faulty.
I recommend calling a service technician to diagnose and repair your washer.
NOTE: Disconnect the power cord from the power source before removing the lower access panel and top panel.
If you do not feel confident repairing this problem yourself, then you can have it repaired at your home by a Sears technician. Here is a link for the website:
Sears Home Services