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Error code reference

Dacor Oven Error Code U24

Upper/single oven ambient temperature probe open

Dacor codesDacor oven codes

Upper/single oven ambient temperature probe open - A/D value of 0XF0 or higher registered on relay board thermistor.

First step from the service manual

Clear error and check oven by running a basic cooking mode. Replace upper relay board.

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

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What U24 means on a Dacor oven

Error code U24 on a Dacor oven indicates that the ambient temperature probe on the upper or single oven relay board has gone open circuit. The relay board contains an onboard thermistor used to monitor the ambient temperature of the board itself, not the oven cavity temperature. When the analog-to-digital converter on the relay board registers a value of 0xF0 or higher, the control interprets this as an open thermistor signal, meaning the probe is no longer returning a valid resistance reading within the expected range.

An open thermistor condition typically occurs when the thermistor has failed internally, breaking the circuit and causing the A/D value to rail at the high end of its scale. This can also result from a wiring harness issue between the thermistor and the relay board, such as a loose connector, a corroded terminal, or a broken wire in the circuit. Because the thermistor is integrated with or mounted on the relay board itself, isolating whether the fault is in the wiring or the board requires careful inspection.

The first diagnostic step is to clear the error code and run a basic cooking mode to see if the fault returns. If U24 reappears, the relay board assembly should be replaced. Because the ambient thermistor is a component of the upper relay board rather than a standalone field-replaceable sensor, the board itself is the primary repair target when wiring and connections have been ruled out.

Source: manufacturer service documentation.

Common causes of U24

  1. 01

    Failed relay board thermistor

    Part replacement

    The onboard ambient thermistor on the upper relay board has failed open internally, causing the A/D value to reach 0xF0 or higher. This is the most likely cause when wiring and connectors check out normal.

  2. 02

    Loose or disconnected wiring connector

    Wiring / connection

    A connector in the thermistor circuit between the relay board and the control system may have worked loose, interrupting the signal. Inspect all connectors at the relay board for proper seating and secure fit.

  3. 03

    Corroded or damaged terminals

    Wiring / connection

    Corrosion or heat damage at terminal pins in the thermistor circuit can create an open condition. Check terminals for discoloration, oxidation, or physical damage that would interrupt continuity.

  4. 04

    Broken wire in the thermistor circuit

    Wiring / connection

    A wire in the harness leading to or from the relay board thermistor may have a break that is not immediately visible. Flex the harness and test for continuity to identify an intermittent or complete break.

  5. 05

    Faulty upper relay board

    Part replacement

    If all wiring and connectors are intact and the error persists after clearing, the relay board itself is likely defective and should be replaced as a complete assembly.

See the test procedure for each cause

Frequently asked questions about U24

What does U24 mean on a Dacor oven?
U24 means the ambient temperature probe on the upper or single oven relay board has gone open circuit. The relay board's onboard thermistor is returning an analog-to-digital value of 0xF0 or higher, which the control reads as an open or missing signal. This is a board-level sensor fault, not a cavity temperature sensor fault. The repair typically involves inspecting wiring connections and, if needed, replacing the upper relay board.
Can I reset the U24 error and keep using my Dacor oven?
You can clear the error and attempt to run a basic cooking mode to see if it returns. If U24 reappears, the underlying fault with the relay board thermistor has not been resolved and the oven should not be used until it is repaired. Continued use without addressing the fault may prevent the oven from operating correctly or cause additional errors.
Is it safe to use my Dacor oven while displaying a U24 error?
A U24 error indicates a monitoring circuit on the relay board is not functioning properly. While this is not the same as a high-temperature runaway condition, operating the oven with a faulty relay board thermistor means a key safety and control circuit is compromised. It is best to clear the error, test the oven once, and have it serviced if the code returns before using it regularly.
How much does it cost to fix a Dacor oven U24 error?
If the fix requires only reconnecting a loose wiring harness or cleaning corroded terminals, the cost is minimal and often just labor time. If the upper relay board needs to be replaced, parts alone typically range from around $150 to $350 or more depending on the model, with professional labor adding to the total. Getting a diagnosis from a qualified technician before ordering parts is recommended.
How do I fix a U24 error on my Dacor oven?
Start by clearing the error code and running a basic cooking cycle to confirm whether the fault is persistent. If U24 returns, inspect the wiring harness and all connectors at the upper relay board for loose connections, corrosion, or damaged wires. If the wiring is intact and the error continues, the upper relay board needs to be replaced. This repair typically requires disassembling the oven's rear or control panel area and should be performed by a qualified technician.

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