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Error code reference

Thermador Range Error Code d:08

WFMC motor control

Thermador codesThermador range codes

WFMC motor control: Motor speed sensor failed (faulty speed sensor or wire harness).

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What d:08 means on a Thermador range

Error code d:08 on a Thermador range indicates a failure in the WFMC motor control system, specifically related to the motor speed sensor. The speed sensor monitors the rotational speed of the motor and sends feedback signals to the motor control board. When the control board cannot receive a valid signal from the speed sensor, or receives a signal that falls outside expected parameters, it triggers this fault code. The WFMC motor control is responsible for regulating motor operation, and without accurate speed feedback, the system cannot confirm proper motor function.

The two primary causes identified for this code are a faulty speed sensor itself or a problem within the wire harness connecting the sensor to the motor control board. A damaged, corroded, or broken speed sensor will fail to generate the proper signal. Similarly, wiring issues such as a broken conductor, loose connector, chafed insulation causing a short, or a corroded terminal can interrupt or corrupt the signal before it reaches the control board.

Diagnosis should focus on physically inspecting the wire harness for visible damage, verifying connector integrity at both the sensor and control board ends, and testing the speed sensor for proper output. If the harness and connectors check out, the speed sensor itself is likely defective and will need replacement. In some cases, the motor control board may also be suspect if wiring and the sensor test correctly.

Source: manufacturer service documentation.

Common causes of d:08

  1. 01

    Faulty motor speed sensor

    Part replacement

    The speed sensor itself may have failed internally and is no longer producing a valid output signal. Testing the sensor output directly can confirm whether it is generating the expected signal during motor operation.

  2. 02

    Damaged or broken wire harness

    Part replacement

    The wiring between the speed sensor and the motor control board may have a broken conductor, chafed insulation, or a short circuit. Visually inspect the harness along its full length for any signs of wear, pinching, or heat damage.

  3. 03

    Loose or corroded connector

    Wiring / connection

    Connector terminals at either the sensor end or the motor control board end can loosen over time or develop corrosion that interrupts the signal. Unplug and reseat each connector and inspect the terminals for oxidation or damage.

  4. 04

    Failed motor control board

    Part replacement

    If the speed sensor and all wiring test correctly, the motor control board may be unable to properly receive or interpret the sensor signal due to an internal board fault. Board failure is less common but should be considered after other components are ruled out.

See the test procedure for each cause

Frequently asked questions about d:08

What does d:08 mean on a Thermador range?
The d:08 error code on a Thermador range indicates that the WFMC motor control has detected a motor speed sensor failure. The control board is not receiving a valid signal from the speed sensor, which monitors motor rotation. The fault points to either a defective speed sensor or a problem with the wire harness connecting the sensor to the control board.
Can I fix the d:08 error code myself?
A knowledgeable DIYer can start by inspecting the wire harness for visible damage and reseating all connectors, which requires no parts and may resolve the issue if a loose connection is the cause. Replacing the speed sensor is a more involved repair that requires identifying and sourcing the correct part. If the motor control board itself is at fault, board replacement is generally a job best handled by a qualified technician.
Is it safe to use my Thermador range while the d:08 code is active?
Operating the range while this fault is active is not recommended, as the motor control system cannot confirm proper motor speed and behavior. Continuing to use the appliance in this state could potentially cause further damage to the motor or control components. It is best to address the fault before resuming normal use.
How much does it cost to repair the d:08 error on a Thermador range?
Repair costs vary depending on which component has failed. A speed sensor replacement part typically falls in the range of $30 to $100 or more depending on the model, while a motor control board can cost considerably more, often in the $150 to $400 range for the part alone. Adding professional labor costs will increase the total, generally ranging from $100 to $250 or more for diagnostics and installation.
Will resetting the Thermador range clear the d:08 error code?
A power reset by disconnecting the range from power for several minutes may temporarily clear the code, but it will return if the underlying hardware fault is not corrected. The speed sensor or wiring issue must be diagnosed and repaired to permanently resolve the error. A reset alone is not a fix and should only be used as part of the diagnostic process.

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