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Error code reference

Thermador Range Error Code E:18

WTMC dryer

Thermador codesThermador range codes

WTMC dryer: NTC error (NTC R2 at heater).

First step from the service manual

Check NTC R2 and wire harness. Replace faulty part.

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 E:18 means on a Thermador range

The E:18 error code on a Thermador WTMC dryer indicates a fault in the NTC temperature sensor designated R2, which is positioned at the heater assembly. NTC stands for Negative Temperature Coefficient, meaning the sensor's electrical resistance decreases as temperature increases. The control board monitors the resistance output from R2 to track heater-area temperatures in real time. When the board receives a signal that falls outside the expected resistance range, either due to an open circuit, a short, or a wildly out-of-spec reading, it logs E:18 and may interrupt normal operation to prevent overheating or component damage.

The most direct cause of this fault is a failed NTC R2 sensor itself. NTC sensors can fail due to prolonged heat exposure, physical damage, or simple component aging, resulting in readings that no longer correspond to actual temperatures. However, the wire harness connecting R2 to the control board is an equally important diagnostic target. Damaged insulation, corroded terminals, loose connector pins, or broken wires in the harness can all produce erroneous resistance readings that mimic a failed sensor. A proper diagnosis requires checking both the sensor and the full harness continuity before replacing any parts.

Diagnostic procedure should begin with a visual inspection of the harness for obvious damage, followed by a resistance measurement of NTC R2 at room temperature to confirm whether it falls within the expected NTC range. If the sensor reads open or shorted, replacement is indicated. If the sensor reads correctly but the error persists, focus shifts to harness integrity and the connector pins at the control board end.

Source: manufacturer service documentation.

Common causes of E:18

  1. 01

    Failed NTC R2 temperature sensor

    Part replacement

    The NTC R2 sensor itself has failed due to heat stress or age, producing a resistance reading outside the acceptable range. This is confirmed by measuring the sensor's resistance with a multimeter and comparing it to expected NTC values.

  2. 02

    Damaged or broken wire harness

    Part replacement

    The wiring connecting NTC R2 to the control board may be broken, chafed, or have corroded terminals, causing an intermittent or incorrect signal. Inspect the full length of the harness and check each connector for corrosion or pushed-back pins.

  3. 03

    Loose or corroded connector at NTC R2

    Wiring / connection

    The connector at the sensor end can work loose over time due to vibration or heat cycling, creating a poor electrical contact that registers as an NTC fault. Reseating and inspecting the connector may resolve the error if no other damage is present.

  4. 04

    Loose or corroded connector at the control board

    Wiring / connection

    The harness connector at the control board end is also subject to corrosion and loosening, which can produce the same erratic resistance signal as a faulty sensor. Check this connection point during any harness inspection.

  5. 05

    Control board unable to read sensor signal

    Part replacement

    In rare cases, the control board's input circuit for the NTC R2 channel may be faulty, causing it to misinterpret a good sensor signal. This should only be considered after the sensor and harness have been fully tested and confirmed functional.

See the test procedure for each cause

Frequently asked questions about E:18

What does E:18 mean on a Thermador range?
E:18 on a Thermador WTMC dryer indicates an NTC error specifically for the R2 temperature sensor located at the heater assembly. The control board has detected that the resistance signal from NTC R2 is outside the acceptable range. This fault causes the appliance to flag the error to prevent unsafe operating temperatures. Both the sensor and its wire harness should be inspected and tested as the first step.
Can I fix the E:18 error myself?
A knowledgeable DIYer can begin by visually inspecting the wire harness and connectors for obvious damage and reseating any loose connections. Measuring the NTC R2 sensor resistance with a multimeter requires basic electrical knowledge and is within reach for experienced DIYers. However, if the sensor or harness needs replacement, and certainly if the control board is suspected, a qualified appliance technician is the safer choice.
Is it safe to keep using the appliance when E:18 appears?
Running the dryer while E:18 is active is not recommended. The NTC R2 sensor is responsible for monitoring temperatures at the heater, and if it is not functioning correctly, the control board cannot reliably regulate heat output. Continuing to operate the unit risks overheating or component damage. The appliance should remain off until the fault is diagnosed and the faulty part is replaced.
How much does it cost to repair the E:18 error on a Thermador dryer?
Repair costs depend on which component has failed. An NTC temperature sensor is generally an inexpensive part, with replacement sensors typically ranging from $15 to $60 depending on the model. If the wire harness requires replacement, parts and labor could range from $80 to $200 or more. A control board replacement, if needed, is significantly more expensive, often $200 to $500 or higher including labor.
Will resetting the dryer clear the E:18 error code?
A power reset may temporarily clear the E:18 code from the display, but the error will return if the underlying fault with NTC R2 or the wire harness has not been corrected. Resetting without addressing the root cause is not a repair. The sensor and harness should be tested and any faulty components replaced before the appliance is returned to regular use.

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