Temperture in wall oven is much hotter then setting

Your wiring diagram and parts schematics are here in the link below. Normally the bottom element does glow read hot after a couple of minutes. Broil elements last a lot longer because they aren't used as much. There is only one Control Board. If I was guessing, I would say the temperature sensor is at fault. Elements either work, or they don't, but you can easily test continuity with a meter. Many parts are discontinued.

https://www.searspartsdirect.com/model/3f7nkrfnvp-001428/frigidaire-pleb30t8ccb-electric-wall-oven-parts

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Sounds like a oven thermostat- thermometer is bad. You can search your oven model number followed by manual
You can find part numbers and location. Or you can search how to replace thermostat for your stove. Good Luck. and stay safe.

Good Morning Friend,

I understand that your Frigidaire oven will not heat to temperature if you set it to 350 degrees. I see that you have to set it to 450 degrees for it to heat up, and then turn it back down to the desired temperature. Please try resetting your appliance, by either unplugging it or shutting the power off at your home's circuit breaker, for 3-5 minutes. Restore power, set the clock and try setting the temperature to 350 degrees. I ask that you please follow up with a comment on the post, at your convenience, to advise if further troubleshooting is needed or if your appliances status has changed successfully. Hope this is helpful.

-Best Regards-
WP

Good Afternoon Andrea,

I see that you're having issues with your Frigidaire oven, and the heating element being red hot the entire time you were cooking no matter how much you turned the temperature down.

I suggest giving your appliance a hard reset. You will do this by either unplugging it or cutting the power off at the circuit breaker for at least 2-3 minutes. When power is restored to your oven, you will need to set the clock by entering in the time and pressing start. Preheat the oven, to whatever desired temperature, and if it is still running hotter than it should be, I suggest you contact your local authorized technician. I hope this is helpful.

-Best Regards-
WP

the oven sensor rod on the rear wall of the oven cavity is defective,remove screws holding it sometimes you can plug a new replacement sensor in from the front,if you can't then remove rear panel on the back of the oven to access the connector to replace it

You can have the oven recalibrated by a professional OR you can purchase an oven thermometer and check the temperature yourself. Place the oven thermometer in the oven.Set the oven to a specific temperature. When it indicates it is at that temperature check the thermometer. Adjust your setting by that many degrees. For instance, if you set the temp at 350 and the oven thermometer shows 450, then reduce your temperature setting by 100 degrees each time you use the oven.

replace the sensor in the oven as it tells the E R C ( clock) what the tempt is and the clock turns of the power . if this does not correct then replac the colck ..mm

On most oven temperture controls, if you pull the knob off there is an adjustment screw down in the shaft turn counterclock wise?? to lower setting. Good luck

The oven thermostst needs replacing, as it is not sensing the correct temperature, this is the switch behind the control knob
Please rate my solution.
Thanks.

It would appear you have a faulty thermostat that controls the temp. SUggest you get a new thermostat fitted.