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Error code reference

Thermador Oven Error Code F33

Upper oven over temperature while cooking.

Thermador codesThermador oven codes

Upper oven over temperature while cooking.

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  • Step-by-step tests with expected resistance, voltage, and continuity values
  • Wiring diagram references and connector pinouts from the OEM service manual
  • Verified part numbers when replacement is required
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What F33 means on a Thermador oven

The F33 error code on a Thermador oven indicates that the upper oven cavity has exceeded its safe operating temperature during a cooking cycle. This is an over-temperature condition, meaning the control system has detected heat levels beyond the acceptable threshold for normal operation. The oven's electronic control board continuously monitors temperature through a sensor probe, and when readings climb past the defined limit, the F33 fault is triggered to prevent potential damage to the appliance or a safety hazard in the kitchen.

The primary components involved in this fault are the oven temperature sensor (also called the RTD probe), the electronic control board, and the oven's heating elements or igniter system. If the temperature sensor is reading incorrectly due to a short or internal fault, it may falsely report extreme temperatures to the control board. Conversely, a runaway heating element or a relay stuck in the closed position on the control board can cause actual overheating, producing a legitimate over-temperature condition.

Common contributing factors include a failed or shorted temperature sensor, a malfunctioning control board relay that keeps the bake or broil element energized continuously, a cooling fan failure that allows heat to build up around the controls, or a damaged door gasket that disrupts proper heat circulation. Proper diagnosis requires checking sensor resistance at room temperature, inspecting element cycling behavior, and verifying control board relay operation.

Source: manufacturer service documentation.

Common causes of F33

  1. 01

    Faulty oven temperature sensor

    Part replacement

    A shorted or internally failed RTD temperature sensor can send incorrect high-temperature readings to the control board, triggering the F33 fault even when the oven is not actually overheating. Resistance can be checked at room temperature to determine if the sensor is out of specification.

  2. 02

    Stuck relay on control board

    Part replacement

    If the relay controlling the bake or broil element on the electronic control board sticks in the closed position, the heating element will remain energized continuously, causing actual runaway overheating. This requires inspection and typically replacement of the control board.

  3. 03

    Failed oven cooling fan

    Part replacement

    The cooling fan circulates air to protect the control electronics and regulate cavity temperature. A seized or failed fan motor can allow heat to accumulate beyond normal operating limits, contributing to an over-temperature fault.

  4. 04

    Damaged or deteriorated door gasket

    Part replacement

    A worn or improperly seated door gasket disrupts the thermal balance inside the oven cavity, potentially causing hot spots and uneven temperature distribution that can contribute to over-temperature conditions at the sensor location.

  5. 05

    Wiring harness short or connection issue

    Wiring / connection

    Damaged wiring or a poor connection between the temperature sensor and the control board can produce erratic resistance readings that the control interprets as an extreme high-temperature event, triggering F33 without an actual overheat condition.

See the test procedure for each cause

Frequently asked questions about F33

What does F33 mean on a Thermador oven?
The F33 code on a Thermador oven means the upper oven detected an over-temperature condition during a cooking cycle. The control board monitors cavity temperature continuously, and this fault is triggered when the temperature exceeds the safe operating limit. It can result from a faulty sensor, a stuck heating relay, or an actual runaway heating situation. The oven should not be used until the root cause is identified and corrected.
Can I fix the F33 error on my Thermador oven myself?
Some causes of the F33 code, such as a loose sensor wiring connection, can be addressed by a knowledgeable DIYer with basic electrical safety awareness. However, diagnosing a stuck relay on the control board or confirming proper sensor resistance values requires a multimeter and familiarity with appliance electrical systems. Replacing the control board involves working near line-voltage components, so if you are not comfortable with that level of repair, a qualified technician is recommended.
Is it safe to keep using my oven when F33 appears?
No, the oven should be taken out of service until the F33 fault is resolved. If the error reflects an actual over-temperature condition caused by a stuck relay or element, continued use could damage internal components or create a fire hazard. Even if the fault is triggered by a faulty sensor rather than true overheating, operating without reliable temperature monitoring is unsafe.
Will resetting the oven clear the F33 error code?
Resetting the oven by turning off the circuit breaker for a few minutes may temporarily clear the F33 code, but it will almost certainly return if the underlying cause has not been corrected. A reset does not repair a failed sensor, fix a stuck relay, or address any other component failure. Use the reset only as part of the diagnostic process, not as a long-term solution.
How much does it cost to repair an F33 error on a Thermador oven?
Repair costs vary depending on the failed component. Replacing a temperature sensor typically runs in the range of $75 to $200 including parts and labor. A control board replacement is more involved and can cost between $300 and $600 or more depending on the model and service rates in your area. Diagnosing the exact cause first is important to avoid replacing parts unnecessarily.

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