Thermador Oven F31 Error: Upper Oven Sensor Open
thermador oven f31 error indicates upper oven sensor open. Stop using the appliance and call a Thermador-certified technician immediately for diagnosis. What Does Thermador Oven Error Code F31 Mean? The F31 error code on Thermador double and combination wall ovens — including C302, CM302, and CJ301 model series — indicates an open circuit in the […]
Quick Assessment
Answer to continue safely
Is it safe to keep using?
Maybe. The lower oven on Thermador double wall oven models is safe to use for all normal cooking while the upper oven F31 fault is being repaired. Do not attempt to bypass the upper oven sensor or force upper oven operation.
Can I reset the code?
No. A reset clears the F31 display but the open circuit remains. F31 returns as soon as the control checks the upper sensor, which happens within seconds of any upper oven cooking program being selected.
When to stop immediately?
Stop if you notice: F31 returns after every reset when any upper oven function is selected, Visible burn damage or charring on the upper RTD sensor probe.
Symptoms You May Notice
Upper oven stays completely cold with no element activity
The upper oven display shows preheat active but no heat develops — the open sensor circuit has caused the control to disable all upper cavity elements.
F31 appears as soon as any upper oven cooking mode is selected
Pressing Bake, Broil, or Convection on the upper oven produces F31 within seconds because the control checks the sensor the moment a program is initiated.
Lower oven functions normally while the upper oven is locked out
The lower cavity of the C302 or CM302 double wall oven continues to heat and cook normally, confirming F31 is isolated to the upper oven sensor circuit.
Possible Causes
Burned-out upper RTD sensor probe
The platinum resistance element inside the upper oven sensor probe has failed open, most commonly after years of self-clean cycles that stress the probe at extreme temperatures.
Requires ProfessionalDisconnected upper sensor harness
The two-wire harness between the control board and the upper oven RTD sensor has come loose at one of its connectors, often after a recent service call where the cavity access panel was removed.
Requires ProfessionalBroken upper sensor wiring
One or both sensor wires have broken or been pinched where they pass through the back wall of the upper cavity, creating an open circuit in the line.
Requires ProfessionalSafe Checks You Can Do
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1
Breaker reset and retest
Switch the oven breaker off for 5 minutes, restore power, and attempt a 250°F Bake on the upper oven. If F31 returns immediately, the upper sensor circuit is genuinely open.
A clean reset rules out a transient connector glitch. Persistent F31 after a reset means the open is physical — harness, probe, or wiring break.
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2
Visually inspect the upper RTD sensor
With the upper oven cool and power off, look at the back wall of the upper cavity. The RTD sensor protrudes about one inch from the rear panel. Check for visible physical damage, charring, or a probe that has separated from the mounting bracket.
Do not pull the probe by its tip — it is secured by screws accessed from the rear panel. A visibly charred or detached probe is diagnostic on its own.
When to Call a Professional
Contact a qualified technician if:
- Upper sensor harness reads infinite resistance on a multimeter when disconnected at the board
- Upper RTD probe is visibly damaged, charred, or separated from its mounting
- Previous self-clean history at high frequency — probe failure rate correlates with clean cycle count
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