The F4 code indicates that there is a problem within the oven temperature sensor control, reports American-Appliance.com. The problem may be either within the wiring, the circuit board or the sensor itself. Diagnosing the problem takes a few steps.
1 Clear the codes on the control panel by pushing "Stop," and try setting and running the oven at cooking temperature. If the oven works, resume using the oven as usual and watch for any further error codes. If the F4 code displays again, the temperature sensor wiring and sensor need to be checked.
2 Pull the range away from wall. Unplug the range's power supply cord from its electrical outlet.
3 Remove the rear panels. There may be only one panel or there may be two panels. The panels could be held in place by locking tabs or by screws. If you see tabs, lift up on the panel and pull it away from the stove. If screws hold it in place, simply remove the screws and the panel.
4 Locate the temperature sensor in the upper right-hand corner of the rear of the stove. The sensor is a metal probe that extends through the rear wall and into the oven. From this view, on the back side of the stove, all that is visible is the probe base and wiring. The base is rectangular, about 1/2 inch by 1 1/2 inches, and held in place on the oven wall by two screws. Depending upon the model of the oven, the temperature sensor will be attached by two screws either on the back side of the stove or inside the oven compartment. A wire is attached to the probe and connects to the oven wiring by two plastic connectors.
5 Check to see if the plastic connectors are firmly pushed and locked together. These connectors are located in the wires attached to the sensor and just a few inches from the sensor. If they are loose and disconnected from each other, this could cause the error code. If the connectors are firmly attached, you will need to replace the temperature sensor.
6 Remove the two screws that secure the sensor to the rear wall of the stove. Carefully pull the sensor out of the stove.
7 Disconnect the sensor wiring by unplugging the plastic connectors. To disconnect the plastic connectors, depress the center tab and pull them apart.
8 Push the new sensor gently into the same hole that the old sensor was removed from. Replace and tighten the two screws that secure the sensor to the stove. Plug the new sensor wiring into the sensor wire connectors.
9 Reattach any rear panels you removed. Plug the power cord into the electrical outlet. Slide the range back into place.