Open sensor circuit or intermittent sensor connection. First you need to check the sensor, to test it disconnect power, pull the range or oven out then take off the back cover. Once off, you should see the two small wires that are from the sensor and you need to disconnect them (some have a plug but if you have to cut the wires). Now using your ohmmeter
, measure resistance between the wires going to the sensor. It should be somewhere between 1050 and 1150 ohms. Note that this test should be done while the oven is at room temperature. If the sensor is open (or not within that range) replace sensor.. you did this but have seen bad sensors new, if not check the wiring between sensor and control. If you don't find any loose connections, the problem may be in the control board but the sensor is much cheaper, so testing with a ohmmeter and cking wiring will totally eliminate that. Sensors and control boards can be purchased at AppliancePartsPros.com
or Repairclinic.com. they who I use. they have online chat and 800# to talk with a tec. if needed before ordering or install questions.
Hopefully tis a bad new sensor or loose wire connection.
Hope this helps a little.