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Error code reference

Thermador Range Error Code F15

Relay board sensor shorted (Gaggenau EB 270/271/290/291).

Thermador codesThermador range codes

Relay board sensor shorted (Gaggenau EB 270/271/290/291).

First step from the service manual

Replace relay board.

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

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  • Wiring diagram references and connector pinouts from the OEM service manual
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What F15 means on a Thermador range

The F15 error code on a Thermador range (specific to Gaggenau EB 270, 271, 290, and 291 models) indicates a shorted sensor condition on the relay board. The relay board is a critical control component responsible for switching power to heating elements and managing communication between the main control board and various oven functions. When the board's internal sensor circuit develops a short, the oven's control system detects an out-of-range signal and triggers this fault to prevent further operation that could damage components or create a safety hazard.

A shorted sensor on the relay board typically means the sensor circuit is reading an abnormally low resistance, effectively pulling the signal line to ground. This differs from an open circuit failure, where resistance would read extremely high or infinite. The short can develop within the relay board's internal circuitry, at a solder joint, or as a result of moisture intrusion or heat damage to the board's components. Because the fault is embedded within the relay board itself rather than in an external wiring harness or standalone sensor, isolation and repair at the component level is generally not practical.

The recommended first diagnostic step is direct replacement of the relay board. Before replacing the board, a technician should visually inspect the board for signs of burning, discoloration, cracked solder joints, or moisture damage. The wiring harness connectors should also be checked for corrosion or damage that could be causing a short to ground externally. If the connectors and harness are intact and undamaged, the relay board itself is the confirmed replacement target.

Source: manufacturer service documentation.

Common causes of F15

  1. 01

    Failed relay board with internal sensor short

    Part replacement

    The most common cause is an internal failure within the relay board itself, where the sensor circuit has shorted. This is not repairable at the component level and requires full board replacement.

  2. 02

    Moisture or liquid intrusion on the relay board

    Part replacement

    Spills or steam infiltration into the oven control cavity can cause corrosion or short circuits on the relay board. Inspect the board for rust, corrosion deposits, or water damage markings.

  3. 03

    Heat damage to relay board circuitry

    Part replacement

    Prolonged exposure to excessive oven heat or a localized hot spot near the board can damage solder joints and traces, causing a sensor circuit short. Look for discoloration or burnt areas on the board surface.

  4. 04

    Damaged or pinched wiring harness causing external short

    Part replacement

    A chafed, pinched, or corroded wire in the harness connecting the relay board can create a short to ground that mimics an internal board fault. Check all connectors and harness routing before replacing the board.

See the test procedure for each cause

Frequently asked questions about F15

What does F15 mean on a Thermador range?
F15 on a Thermador range indicates a shorted sensor on the relay board. This fault applies specifically to Gaggenau EB 270, 271, 290, and 291 model variants. The oven's control system has detected an abnormal short circuit condition within the relay board's sensor circuit and has halted operation as a protective measure.
Can I fix the F15 error myself on a Thermador range?
The repair requires replacing the relay board, which involves working with high-voltage oven components. A qualified appliance technician is strongly recommended for this repair. An experienced DIYer comfortable with appliance electronics could attempt it after disconnecting power at the breaker, but sourcing the correct relay board for the specific EB model variant is essential.
Is it safe to use my Thermador range while it shows F15?
No, you should not attempt to operate the oven while the F15 code is active. The fault indicates a short circuit condition within the relay board, which could lead to component damage or unpredictable oven behavior. Disconnect power to the range until the relay board has been inspected and replaced.
Will resetting the oven clear the F15 error code?
A power reset by turning off the breaker for several minutes may temporarily clear the code, but it will return once the oven attempts to operate because the underlying short circuit in the relay board remains present. A reset does not fix the hardware fault and is not a reliable solution.
How much does it cost to fix a Thermador range F15 error?
Repair costs typically depend on the price of the relay board part and labor rates in your area. Parts for specialty European-style ranges like the Gaggenau EB series can range from around $150 to $400 or more, and professional labor can add another $100 to $250 depending on the technician and region. Getting a diagnostic quote from an authorized technician before committing to the repair is advisable.

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