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Error code reference

Thermador Oven Error Code F3

Open sensor circuit; displays only when oven is in heat mode

Thermador codesThermador oven codes

Open sensor circuit; displays only when oven is in heat mode. If oven is off, cooling fans will continue to run.

First step from the service manual

Correct the open sensor circuit problem or trip house circuit breaker to shut off cooling fans.

The complete diagnostic procedure includes additional test steps, resistance specifications, wiring diagram references, and component test points.

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What F3 means on a Thermador oven

The F3 error code on a Thermador oven indicates an open sensor circuit in the oven temperature sensing system. This fault is specifically triggered when the oven is actively in heat mode, meaning the control board is attempting to read temperature data from the oven temperature sensor (RTD probe) but is receiving no signal. An open circuit condition means the electrical path between the sensor and the control board has been broken, preventing any temperature feedback from reaching the control system.

The oven temperature sensor is a resistance-based probe, typically a platinum RTD (resistance temperature detector), that changes its resistance value in proportion to temperature. Under normal operating conditions, the control board monitors this resistance to regulate heating elements. When the circuit is open, resistance reads as infinite, which the board interprets as a sensor fault and triggers F3. Common causes include a failed sensor probe, a break or burn in the sensor wiring harness, or a corroded/loose connector at either the sensor end or the control board end.

A notable behavior associated with this code is that the cooling fans will continue to run even after the oven is powered off, because the control system cannot confirm safe cavity temperatures without sensor input. The immediate corrective action is either to resolve the open circuit fault or to trip the house circuit breaker to cut power and stop the fans. Simply pressing cancel or turning the oven off at the control panel will not halt the cooling fans while F3 is active.

Source: manufacturer service documentation.

Common causes of F3

  1. 01

    Failed oven temperature sensor

    Part replacement

    The RTD temperature probe inside the oven cavity can fail internally, creating an open circuit. A multimeter check of the sensor's resistance will show an out-of-range or infinite reading if the probe has failed.

  2. 02

    Broken or damaged sensor wiring harness

    Part replacement

    The wires connecting the sensor probe to the control board can crack, burn, or break, especially near connection points or if they have been pinched. Visually inspect the harness for any obvious damage and use a multimeter to check continuity along the wire run.

  3. 03

    Loose or corroded sensor connector

    Wiring / connection

    The connector at the back of the sensor probe or at the control board can work loose or corrode over time, interrupting the circuit. Unplug and firmly reseat both connectors and inspect the terminals for corrosion or bent pins.

  4. 04

    Damaged control board sensor input

    Part replacement

    If the sensor and wiring check out correctly, the fault may lie with the control board's sensor input circuit, which can be damaged by voltage spikes or component failure. This is less common but should be considered after ruling out the sensor and harness.

See the test procedure for each cause

Frequently asked questions about F3

What does F3 mean on a Thermador oven?
F3 on a Thermador oven indicates an open sensor circuit in the oven temperature sensing system. The fault activates only when the oven is in heat mode and the control board cannot receive a signal from the temperature sensor. It points to a break somewhere in the circuit path between the sensor probe and the control board. The cooling fans will continue to run after the oven is turned off until the fault is corrected or power is cut at the breaker.
Can I fix the F3 error myself, or do I need a technician?
Some causes of F3 are DIY-friendly, such as reseating a loose connector at the sensor or control board. Testing and replacing the oven temperature sensor probe is also a task many experienced DIYers can handle with basic tools and a multimeter. However, if the wiring harness is damaged or the control board is at fault, professional repair is recommended to avoid further damage.
Is it safe to use my oven while the F3 code is showing?
No, you should not attempt to use the oven while F3 is active. Because the temperature sensor circuit is open, the control board has no way to monitor or regulate the oven temperature, which creates a risk of overheating. Stop using the oven and address the fault before resuming normal operation.
Will resetting the oven clear the F3 error code?
A reset by turning the oven off at the control panel will not clear F3 or stop the cooling fans while the open sensor circuit remains. Tripping the house circuit breaker will cut power and stop the fans, but the code will return as soon as the oven is powered back on and attempts to heat. The underlying open circuit fault must be corrected to permanently clear F3.
How much does it cost to repair a Thermador oven F3 error?
Repair costs depend on which component has failed. A replacement oven temperature sensor probe typically costs in the range of $20 to $80 for the part, with additional labor if a technician performs the work. A wiring harness repair or control board replacement will cost more, generally ranging from $150 to $400 or higher depending on parts and labor rates in your area.

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