Since oven temperatures fluctuate as the heating element cycles on and off, you’ll need to take multiple thermometer readings and calculate the average to determine the actual temperature. The more readings you record, the more accurate your average will be (professionals often take at least five readings).
Follow these steps to accurately measure your oven’s temperature:
1. Use a reliable oven thermometer for this task.
2. Place the thermometer on the middle rack and set the oven to 350°F.
3. Allow the oven to preheat, then wait an additional 10 minutes for the temperature to stabilize after the initial spike.
4. Check the thermometer reading through the oven window and record it on paper.
5. Wait 10 minutes, then take another reading. Repeat this process several times, recording each reading.
6. Add all the recorded temperatures and divide by the number of readings to calculate the average oven temperature.
Knowing your oven’s actual temperature will help you determine if calibration is needed and by how much, ensuring consistent and accurate baking results. 
If your oven isn’t heating correctly and adjusting the oven control doesn’t solve the issue, the problem may lie with a faulty temperature sensor or control system.
At room temperature, the oven temperature sensor should typically measure approximately 1080 ohms of resistance.
Here’s a resistance chart used by technicians to verify the accuracy of the oven temperature sensor: 
If the measured resistance of the temperature sensor deviates by more than 100 ohms from the expected value, it’s likely time to replace the sensor. This ensures your oven operates efficiently and maintains accurate temperatures. 
