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Error code reference

Thermador Range Error Code F13

Power board not calibrated; air switch may be jammed (C, CM, CJ ovens). Also

Thermador codesThermador range codes

Power board not calibrated; air switch may be jammed (C, CM, CJ ovens). Also: Upper oven RTD not calibrated (Sago control).

First step from the service manual

Check if air switch is jammed; if OK replace power/relay board.

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

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What F13 means on a Thermador range

The F13 error code on Thermador ranges indicates a calibration fault in the power or relay board. On models designated C, CM, and CJ, the code specifically points to an uncalibrated power board, often triggered by a jammed or stuck air switch. The air switch is a pressure-sensitive component that monitors airflow through the oven cavity or cooling system. When this switch becomes mechanically stuck, it can send incorrect signals to the control board, causing the system to flag a calibration failure even if the board itself is fully functional.

On ranges equipped with the Sago control system, the F13 code carries a different but related meaning: the upper oven RTD (resistance temperature detector) sensor is reporting an uncalibrated condition. The RTD is responsible for monitoring oven temperature and feeding that data back to the control. If the RTD is out of calibration range or has developed a resistance reading outside expected parameters, the Sago control will trigger F13 to indicate that accurate temperature regulation is no longer possible.

Diagnosis should begin by physically inspecting the air switch for signs of jamming, debris obstruction, or a stuck plunger. If the air switch moves freely and tests correctly, attention shifts to the power or relay board, which may require replacement. On Sago-equipped units, RTD resistance should be measured and compared against specification before condemning the control board itself.

Source: manufacturer service documentation.

Common causes of F13

  1. 01

    Jammed or stuck air switch

    Wiring / connection

    The air switch plunger can become mechanically stuck due to debris, grease buildup, or corrosion. A stuck switch sends a continuous or incorrect signal to the power board, triggering the calibration fault.

  2. 02

    Faulty or uncalibrated power/relay board

    Part replacement

    If the air switch inspects as fully functional, the power or relay board itself may have lost its calibration data or developed an internal fault. Replacement of the board is typically required in this scenario.

  3. 03

    Upper oven RTD out of calibration range (Sago control models)

    Part replacement

    On Sago control-equipped ranges, the RTD temperature sensor may be reading outside its acceptable resistance window, causing the control to flag an F13 calibration error. The RTD should be tested with a multimeter to confirm its resistance values.

  4. 04

    Wiring fault between air switch and power board

    Wiring / connection

    Loose connectors, burned terminals, or damaged wiring between the air switch and the power board can interrupt the calibration signal and produce an F13 code even when both components are individually functional.

  5. 05

    Failed RTD sensor (Sago control models)

    Part replacement

    If the upper oven RTD has completely failed rather than simply drifted out of calibration, it will need to be replaced before the Sago control can clear the F13 fault and resume normal operation.

See the test procedure for each cause

Frequently asked questions about F13

What does F13 mean on a Thermador range?
F13 indicates a calibration fault involving either the power board or a related component. On C, CM, and CJ oven models, it typically means the power board is not calibrated, often because the air switch is jammed. On Sago control models, F13 points to the upper oven RTD sensor being out of calibration.
Can I fix the F13 error myself, or do I need a technician?
Checking the air switch for physical jamming or obstruction is something a confident DIYer can attempt after disconnecting power to the range. However, testing RTD resistance values, diagnosing relay board faults, and replacing internal components typically require familiarity with appliance wiring and should be handled by a qualified technician if you are not comfortable with those procedures.
Is it safe to use my Thermador range while it shows the F13 code?
It is not recommended to continue using the oven while F13 is active. The code indicates that the oven cannot confirm accurate temperature calibration, which means cooking temperatures may be unreliable. On Sago control models, an uncalibrated RTD could lead to significant temperature deviation during operation.
Will resetting the range clear the F13 error code?
A power reset by unplugging the range or switching off the circuit breaker for a few minutes may temporarily clear the F13 code, but it will return if the underlying fault is not corrected. The air switch, RTD, or power board issue must be resolved for the error to be permanently cleared.
How much does it typically cost to repair a Thermador F13 error?
Repair costs depend on which component is at fault. If the air switch is simply jammed and can be freed without replacement, costs may be limited to a diagnostic service call, typically in the range of $75 to $150. Replacing the power or relay board can add $150 to $400 or more in parts, while RTD sensor replacement generally falls in the $50 to $150 range for the part, plus labor.

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