stoves with an electrode start igniter do not lite up pilot by adding a flame, that will not work. u need to find out why and where is the power to igniter is not coming from? the spark module or a bad igniter?
The parts diagram here, https://www.appliancepartspros.com/oven-parts-for-whirlpool-ggp84800.html , lists the oven temperature as part 8. That is Whirlpool part AP6011627. Note: the F3 error indicates that the ERC (electronic range control/clock) isn't getting the message from the temperature sensor. It can also occur if the wiring is damaged or the ERC is faulty. You may want to check for damaged wiring if the new sensor doesn't cure the F3 error. Then check the ERC pins where the temperature sensor connects to it.
If the error persists, the only solution is usually to replace the ERC. The ERC for the GGP84800 is not be available any longer as a new part. You may be able to get a remanufactured ERC.
I hope this helps.
If the oven won't turn off the oven thermostat is often the cause of the problem. The electrical contacts inside the oven thermostat can weld themselves together and then the oven won't turn off. If this happens, turn off power to the entire appliance at the household circuit breaker or fuse. The oven thermostat usually cannot be tested and must be replaced if defective.
Oven Control Board
The oven control board has a set of relays that turn on and off power to the bake and broil circuits according to the customer settings and sensor input. If the oven won't turn off it could be that one of the relays on the oven control board is shorted closed, providing voltage to the heating circuit. It can be dangerous if the oven won't turn off. Don't leave the oven unattended without turning off power to the oven.
Some ovens are equipped with a relay board. This circuit board has several relays which control the switching of electrical current to the oven heat source. If the oven won't turn off it may be that one or more of the relays on the relay board have failed. If this happens replace the relay board. The relays on the board are not sold separately. ALSO CHECK THE BAKE AND BROIL ELEMENT.