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Error code reference

Thermador Oven Error Code E204

Lower cavity (Cvt 2) temperature sensor shorted.

Thermador codesThermador oven codes

Lower cavity (Cvt 2) temperature sensor shorted.

First step from the service manual

Refer to Diagram 2/4.

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

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What E204 means on a Thermador oven

Error code E204 on a Thermador oven indicates that the temperature sensor for the lower cavity (identified in Thermador documentation as Cvt 2, or Cavity 2) has experienced a short circuit condition. A shorted sensor means the sensor's internal resistance has dropped to near zero ohms, which causes the oven's control board to receive a voltage signal that falls outside the expected operating range. The control interprets this abnormal signal as a fault and locks out normal operation to prevent unsafe temperature conditions or component damage.

The lower cavity temperature sensor is a negative temperature coefficient (NTC) thermistor or a resistance temperature detector (RTD) type probe, depending on the specific Thermador model. Under normal conditions, this sensor produces a predictable resistance value that corresponds to the cavity temperature, allowing the control board to regulate heating elements accurately. A short circuit in this sensor circuit eliminates that resistance relationship entirely, making accurate temperature control impossible.

Diagnosing E204 requires referencing Diagram 2/4 specific to the unit, which maps the wiring connections between the lower cavity sensor and the main control board. Common entry points for the fault include the sensor probe itself, the wiring harness running from the sensor to the control board, or the connector terminals at either end of that circuit. Technicians should inspect the harness for pinched, burnt, or melted insulation, and measure sensor resistance with a multimeter to confirm whether the sensor or the wiring is the root cause.

Source: manufacturer service documentation.

Common causes of E204

  1. 01

    Failed lower cavity temperature sensor

    Part replacement

    The sensor probe itself has developed an internal short, causing its resistance to drop to near zero. Confirm by disconnecting the sensor and measuring its resistance with a multimeter. A shorted sensor will read close to 0 ohms rather than the expected value for its temperature.

  2. 02

    Damaged or pinched wiring harness

    Part replacement

    The wiring between the lower cavity sensor and the control board may be pinched, melted, or abraded, causing two conductors to contact each other and create a short. Inspect the harness routing, particularly where it passes through the oven frame or near heat sources.

  3. 03

    Corroded or shorted connector terminals

    Wiring / connection

    Moisture, grease, or heat degradation at the sensor connector or the control board connector can cause terminal pins to short against each other. Inspect both connector ends for discoloration, corrosion, or debris bridging the contacts.

  4. 04

    Control board fault

    Part replacement

    In less common cases, a failure on the control board's sensor input circuit can produce a false short reading even when the sensor and wiring are intact. This is typically diagnosed only after the sensor and harness have been confirmed good.

See the test procedure for each cause

Frequently asked questions about E204

What does E204 mean on a Thermador oven?
E204 indicates a shorted temperature sensor in the lower oven cavity, referred to as Cvt 2 or Cavity 2 in Thermador schematics. A shorted sensor means its resistance has collapsed to near zero, preventing the control board from accurately reading the oven temperature. The oven displays this code and suspends normal operation to avoid unsafe conditions. Diagnosis should begin with the wiring diagram labeled Diagram 2/4 for the specific unit.
Can I reset the oven to clear the E204 error?
Cycling power to the oven by turning off the circuit breaker for 30 seconds may temporarily clear the error display, but the code will return if the underlying short circuit in the lower cavity sensor circuit is still present. A reset does not repair a failed sensor or damaged wiring. The root cause must be identified and corrected before the oven will operate normally.
Is it safe to use my Thermador oven while it shows E204?
It is not recommended to continue using the oven while E204 is active. The lower cavity temperature sensor is essential for accurate heat regulation, and a shorted sensor means the control board cannot monitor oven temperature correctly in that cavity. Continuing to operate the oven in this condition could result in uncontrolled heating or further component damage.
How much does it cost to fix a Thermador oven E204 error?
Repair costs depend on which component has failed. A replacement lower cavity temperature sensor typically costs in the range of $30 to $80 for the part alone. If the control board requires replacement, parts can range from $150 to $400 or more depending on the model. Adding professional labor, total repair costs generally fall between $150 and $500, with more complex wiring or board repairs at the higher end.
How do I diagnose whether the sensor or the wiring is causing E204?
Start by disconnecting the lower cavity sensor connector and measuring the sensor's resistance with a multimeter. A shorted sensor will read near 0 ohms. If the sensor reads a normal resistance value, reconnect it and then inspect the wiring harness between the sensor and the control board for pinched or melted insulation. Referencing Diagram 2/4 for the specific model will show the correct connector locations and circuit path to test.

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