Most oven sensors have a mounting plate that is attached to the rear wall of the oven cavity interior. That mounting plate is usually held in place by 2 screws which go through it into the rear oven liner to hold it in place.
Testing the Oven Sensor
Testing of the sensor has to be performed while the problem is occurring. If the problem is present as soon as an oven function is selected and even before heating has begun, the sensor itself can be tested to see if it is within specs. The most common oven sensor currently used should measure approximately 1080 ohms when at room temperature. See below for a detailed temperature/resistance chart.
Once power has been disconnected from the appliance (do NOT just rely on the controls being off!), the sensor mounting screws can be removed. The mounting screws can sometimes be rusted or seized in place so make sure a good screwdriver is used so the screw heads don't get stripped in the process.
Once the retaining screws have been removed, the sensor should be able to be pulled (at least slightly) into the oven cavity. There should be a plastic terminal block on the wires which may have to be manipulated to get it through the hole in the rear of the oven cavity. Once through, the connector can be disconnected to access the sensor wire terminals to perform a resistance test of it.