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Error code reference

Thermador Cooktop Error Code E0240

Power board error checking induction module component: input relay

Thermador codesThermador cooktop codes

Power board error checking induction module component: input relay — same as E0236.

First step from the service manual

See error E0236 troubleshooting steps.

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

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What E0240 means on a Thermador cooktop

Error code E0240 on a Thermador induction cooktop signals a power board fault during its self-check of the induction module's input relay. The power board continuously monitors the input relay to confirm it is opening and closing as commanded. When the board detects an anomaly in relay behavior, such as a failure to switch states, unexpected resistance readings, or a signal that falls outside the expected parameters, it logs E0240 and halts operation to prevent damage to downstream induction components.

The input relay is a critical switching component that controls the flow of AC power into the induction module. If the relay contacts are welded shut, have failed open, or if the relay coil has developed a fault, the power board cannot verify proper operation and throws this error. Wiring integrity between the power board and the relay is equally important, as a broken connection, corroded terminal, or loose harness connector can mimic a relay failure and produce the same code.

Because E0240 is functionally identical to E0236, all diagnostic procedures developed for E0236 apply directly here. Both codes trace back to the same input relay monitoring circuit on the power board. Technicians should follow the E0236 troubleshooting sequence in full, including visual inspection of the relay, continuity checks on the wiring harness, and evaluation of the power board itself if the relay and wiring check out as serviceable.

Source: manufacturer service documentation.

Common causes of E0240

  1. 01

    Failed input relay

    Part replacement

    The input relay contacts may be welded shut, burned open, or the relay coil may have failed. This is the most direct cause and can often be confirmed by testing the relay for proper switching and continuity.

  2. 02

    Loose or damaged wiring harness

    Wiring / connection

    A connector that has worked loose or a wire with corrosion or damage between the power board and the relay can cause the board to read an incorrect relay state. Inspect all connectors and harness conductors in the relay circuit for physical damage.

  3. 03

    Power board fault

    Part replacement

    If the relay and all associated wiring test correctly, the power board itself may have a defective relay driver circuit or a failed monitoring component. This would cause the board to misread or fail to control the relay.

  4. 04

    Voltage supply issue

    Wiring / connection

    Insufficient or unstable voltage reaching the power board can interfere with relay switching logic. Verify that the cooktop is receiving the correct supply voltage at the terminal block before replacing components.

See the test procedure for each cause

Frequently asked questions about E0240

What does E0240 mean on a Thermador cooktop?
E0240 indicates that the power board detected an error while checking the induction module's input relay. The relay is responsible for switching AC power into the induction components, and the board was unable to confirm it is operating correctly. This code is functionally the same as E0236 and uses the same diagnostic approach.
Will resetting the cooktop clear the E0240 error?
A power reset may temporarily clear E0240, but the code will return if the underlying fault is still present. Cycling power does not repair a failed relay, damaged wiring, or a faulty power board. A proper diagnosis of the input relay circuit is needed to resolve the error permanently.
Is it safe to use the cooktop while E0240 is displayed?
No. The cooktop locks out operation when E0240 is active because the power board cannot confirm the input relay is functioning correctly. Attempting to bypass this lockout is not recommended, as the relay fault could pose a risk to the induction module and other internal components.
How do I fix E0240 on a Thermador induction cooktop?
Follow the same diagnostic steps used for error E0236. Begin by inspecting the input relay for physical damage and testing it for proper switching. Check all wiring and connectors between the relay and the power board for corrosion or looseness. If the relay and wiring are sound, the power board may need to be replaced.
How much does it cost to repair a Thermador cooktop showing E0240?
Repair costs depend on which component has failed. Relay replacement parts are generally in the range of $20 to $80, while a power board replacement can run between $150 and $400 or more depending on the model. Adding professional labor typically brings the total repair cost to somewhere between $200 and $600.

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