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Error code reference

Dacor Oven Error Code U20

Upper oven over temperature

Dacor codesDacor oven codes

Upper oven over temperature - center of cell temperature over 610°F for 2 minutes during cook mode.

First step from the service manual

Verify probe readings, verify cycling/timing charts, verify calibration values to software version. Put thermocouple in center of oven and verify values are averaging +/- 10°F of target.

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

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What U20 means on a Dacor oven

The U20 error code on a Dacor upper oven indicates that the center-of-cell temperature has exceeded 610°F for a continuous period of two minutes while the oven is in cook mode. This is an over-temperature fault, meaning the oven's thermal monitoring system has detected that actual cavity temperatures are running significantly above the intended setpoint. The control board uses temperature input from the oven sensor circuit to track cavity heat, and when readings sustain above the 610°F threshold beyond the two-minute window, the U20 fault is triggered and normal operation is interrupted.

The most common contributors to this fault are a failed or drifting oven temperature sensor, a stuck or shorted relay on the control board that allows continuous power delivery to the bake or broil element, or a calibration mismatch between the software version loaded on the control and the expected sensor offset values. Because the diagnostic procedure specifically calls for verifying calibration values against the software version, it is important to confirm that the installed software and calibration parameters are aligned before replacing hardware.

Diagnosis begins by placing a calibrated thermocouple in the center of the oven cavity and comparing live readings against the programmed target temperature. The thermocouple readings should average within plus or minus 10°F of the target. If actual temperatures are consistently and significantly higher than the setpoint, the technician should review the cycling and timing charts for the heating elements, check the temperature sensor for accuracy and correct resistance, and confirm calibration values match the current software version on the control board.

Source: manufacturer service documentation.

Common causes of U20

  1. 01

    Faulty oven temperature sensor

    Part replacement

    A drifting or failed temperature sensor can report inaccurate readings, causing the control to allow overheating or falsely trigger the U20 fault. Placing a calibrated thermocouple in the center of the cavity and comparing it against sensor readings will reveal whether the sensor is out of spec.

  2. 02

    Calibration mismatch with software version

    Wiring / connection

    If the calibration offset values stored in the control do not match what the installed software version expects, the control may misinterpret temperature data and allow temperatures to run too high before reacting. Always verify that calibration values correspond to the current software version as a first diagnostic step.

  3. 03

    Stuck or shorted relay on the control board

    Part replacement

    A relay on the control board that stays closed or partially shorted can deliver continuous power to a heating element even when the control is commanding it off, resulting in runaway temperature rise. Reviewing cycling and timing charts for the element will help identify whether the element is cycling correctly.

  4. 04

    Bake or broil element short circuit

    Part replacement

    A shorted heating element can draw excessive power and drive oven temperatures well above the target setpoint. Visual inspection for burn marks or blistering on the element surface, along with resistance testing, can confirm this condition.

  5. 05

    Incorrect oven calibration offset programmed by user

    Wiring / connection

    If a user-set calibration offset has been applied that shifts the target temperature significantly upward, the oven may operate at temperatures high enough to trigger the U20 threshold. Checking the current calibration offset in the settings and resetting it to zero is a quick verification step.

See the test procedure for each cause

Frequently asked questions about U20

What does U20 mean on a Dacor oven?
The U20 code means the upper oven exceeded 610°F at the center of the cavity for two or more minutes during cook mode. This is an over-temperature protection fault that halts oven operation to prevent damage or a safety hazard. It points to a problem with the temperature sensor, control board relay, or a calibration mismatch between the software version and stored calibration values.
Can I fix a U20 error on my Dacor oven myself?
Some parts of the diagnosis, such as checking the calibration offset setting or resetting the control, can be done without special tools. However, fully diagnosing this fault requires a calibrated thermocouple to verify actual cavity temperatures, plus knowledge of how to interpret cycling charts and resistance values. If the issue involves a faulty sensor, control board relay, or software calibration mismatch, a qualified technician should handle the repair.
Is it safe to use my Dacor oven when the U20 code is showing?
No, you should not continue using the oven while this code is active. The U20 fault indicates the oven has already reached temperatures above 610°F during a cooking cycle, which is well outside normal operating range. Using the oven in this condition could cause damage to internal components or create a fire hazard.
Will resetting the oven clear the U20 error code?
Resetting the control by cycling power may temporarily clear the code, but it will return if the underlying cause is not corrected. The fault is triggered by a sustained over-temperature condition, so simply resetting the unit without diagnosing the root cause means the oven is likely to fault again during the next cooking cycle. A proper repair requires verifying sensor accuracy, calibration values, and element cycling behavior.
How much does it cost to repair a Dacor oven showing a U20 error?
Repair costs depend heavily on the root cause. A temperature sensor replacement is typically the least expensive fix, often ranging from around $100 to $250 including parts and labor. A control board replacement involving a stuck relay can range from $300 to $600 or more depending on the specific model and part availability. A service call for diagnosis alone generally runs between $75 and $150 before any parts are factored in.

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