How to Test an Oven Temperature Sensor (RTD)
When an oven won't hold temperature, heats wrong, or throws an F2, F3, F4, F10, or F30 code, the oven temperature sensor (a resistance probe called an RTD) is the first thing to test. It's a cheap part and an easy test — you just need a multimeter. Before condemning an expensive control board, confirm the sensor.
What the Oven Sensor Does
The oven temperature sensor is a thin metal probe that sticks into the oven cavity, usually at the upper-rear. It's an RTD (resistance temperature detector): its electrical resistance changes predictably with temperature. The control board reads that resistance to know how hot the oven is and when to cycle the heating elements. If the sensor drifts, opens, or shorts, the oven can overheat (F2/F10), under-heat, or refuse to run (F3/F4/F30).
Step 1: Unplug and Access the Sensor
Turn off and unplug the oven (or shut off the breaker). The sensor is held by two screws inside the oven at the back. Remove the screws, pull the probe into the cavity, and unplug its connector — the connector is usually just behind the rear oven wall. You can test it in place at the connector, or remove it.
Step 2: Measure Resistance at Room Temperature
Set your multimeter to ohms (200 or 2k range). Touch the probes to the sensor's two terminals. Most ovens use a 1000-ohm RTD that reads very close to 1080-1090 ohms at room temperature (around 68-75°F). A reading near that range means the sensor is good. A reading of 0, infinite/OL (open), or wildly off means the sensor has failed and should be replaced.
Step 3: Confirm With Heat (Optional)
An RTD's resistance rises as it heats. If you carefully warm the probe (e.g., with a hair dryer), the resistance should climb smoothly. A sensor whose resistance jumps erratically or doesn't change is faulty. Roughly, these sensors gain about 2 ohms per °F.
Step 4: Replace if Out of Spec
Oven temperature sensors are inexpensive and model-specific — match the part number to your oven. Installation is the reverse of removal: plug in the connector, feed the probe back through the rear wall, and screw it into place. If the sensor tests good but the code persists, the next suspect is the control board (a stuck relay can cause over-temp codes even with a good sensor).
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FAQ
Most ovens use a 1000-ohm RTD that reads about 1080-1090 ohms at room temperature. Open (OL), zero, or a reading far from that range indicates a bad sensor.
Yes. A sensor reading low makes the control over-fire the oven, which can trigger an over-temperature code like F2 or F10. Always test the sensor before replacing the control board.
The part is usually $15 to $40 and is one of the easiest oven repairs — two screws and a connector.
Always unplug an appliance and shut off its water supply before servicing. This guide is informational and not a substitute for a qualified technician.