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Error code reference

Dacor Range Oven Cooktop Error Code U23

Over temperature (upper/single oven)

Dacor codesDacor range oven cooktop codes

Over temperature (upper/single oven) - ambient temp around relay board is too high.

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What U23 means on a Dacor range oven cooktop

The U23 error code on Dacor ranges and ovens signals an over-temperature condition specific to the upper or single oven cavity, with the critical distinction that the excessive heat is being detected at the relay board itself, not just within the oven chamber. The relay board is responsible for switching power to the bake and broil elements, and it is typically mounted in a location that receives cooling airflow from the unit's ventilation system. When the ambient temperature surrounding this board climbs beyond its rated threshold, the control system triggers U23 to protect the board's components from heat-related damage or failure.

The most common underlying cause is a failure in the oven's cooling fan circuit. Dacor ovens use one or more cooling fans to draw ambient air through the control cavity and exhaust heat away from sensitive electronics. If the cooling fan motor has seized, a fan blade is obstructed, or the fan's wiring harness has developed an open circuit, airflow to the relay board is reduced or eliminated entirely. Extended high-temperature baking or self-clean cycles are particularly likely to trigger U23 when cooling is inadequate.

Additional causes include blocked ventilation pathways due to improper installation clearances, a relay board mounted incorrectly after prior service, or actual component failure on the relay board itself causing localized heat buildup. In some cases, an oven that genuinely overheats due to a faulty temperature sensor or a stuck relay can raise the overall internal temperature to the point where the relay board's environment exceeds safe limits, producing U23 as a secondary symptom of a primary thermal runaway condition.

Source: manufacturer service documentation.

Common causes of U23

  1. 01

    Cooling fan failure

    Part replacement

    The cooling fan responsible for circulating air around the relay board may have a seized motor, a broken blade, or a failed wiring connection. Without airflow, heat accumulates around the board rapidly, especially during or after long cook cycles.

  2. 02

    Blocked or restricted ventilation

    Wiring / connection

    Insufficient clearance around the range or oven, or blocked vent openings, can prevent the cooling system from exhausting heat effectively. Check that installation clearances meet Dacor specifications and that no debris is obstructing vents.

  3. 03

    Faulty oven temperature sensor causing thermal runaway

    Part replacement

    A defective oven temperature sensor can allow the oven cavity to exceed its intended temperature, raising the overall internal heat level to a point where the relay board's environment becomes too hot. This makes U23 a secondary symptom of a primary sensor problem.

  4. 04

    Stuck or failed relay on the relay board

    Part replacement

    A relay that fails in the closed position will allow continuous power to a heating element, causing the oven to overheat. This sustained elevated temperature can drive ambient heat at the board above safe levels, triggering U23.

  5. 05

    Relay board failure or incorrect installation

    Part replacement

    The relay board itself may have failed in a way that generates excess heat internally, or it may have been remounted incorrectly after prior service, disrupting the intended airflow path around it.

See the test procedure for each cause

Frequently asked questions about U23

What does U23 mean on a Dacor range, oven, cooktop?
U23 indicates that the ambient temperature around the relay board in the upper or single oven has exceeded a safe threshold. The relay board controls power to the oven's heating elements, and this code means the control system has detected dangerously high heat in that area. The oven shuts down to prevent damage to the electronics. The root cause is typically a cooling fan problem or a ventilation restriction.
Is it safe to use my Dacor oven when the U23 code is displayed?
No, you should not continue operating the oven while U23 is active. The code indicates the relay board is being exposed to excessive heat, which can cause permanent damage to the electronics and potentially create a fire risk if a relay is stuck on and the oven is overheating. Power the unit off and allow it to cool completely before attempting any diagnosis.
Will resetting my Dacor oven clear the U23 error code?
Resetting the oven by cycling the power at the breaker may temporarily clear the U23 code once the unit cools down, but if the underlying cause is not repaired, the code will return. A reset does not fix a failed cooling fan, a blocked vent, or a faulty relay. Treat a recurring U23 as a persistent mechanical or electrical problem that requires hands-on diagnosis.
How do I fix the U23 error code on my Dacor oven?
Start by allowing the oven to cool completely, then check that all ventilation openings are unobstructed and that the unit has proper installation clearances. Listen for the cooling fan during operation since a silent or intermittent fan is a strong indicator of motor failure. If the fan is running normally, the next step is checking the oven temperature sensor and inspecting the relay board for signs of heat damage or a stuck relay. A repair technician will be needed for component-level diagnosis and any parts replacement.
How much does it cost to repair a Dacor oven showing the U23 error?
Repair costs vary depending on the failed component. A cooling fan motor replacement typically falls in the range of $150 to $350 including parts and labor. Relay board replacement can range from $250 to $600 or more depending on the specific board and labor rates in your area. An oven temperature sensor is generally one of the less expensive components to replace, often in the $100 to $250 range. Obtaining a diagnostic service call first is recommended to confirm the exact cause before committing to parts.

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