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Error code reference

Dacor Oven Error Code U25

Upper/single oven ambient temperature probe shorted

Dacor codesDacor oven codes

Upper/single oven ambient temperature probe shorted - A/D value of 0X10 or lower registered.

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 U25 means on a Dacor oven

The U25 error code on a Dacor oven indicates that the ambient temperature probe in the upper or single oven cavity has registered a shorted condition. Specifically, the analog-to-digital converter on the relay board has read a value of 0x10 (hexadecimal 16) or lower, which falls below the threshold associated with a valid resistance signal. The ambient temperature probe is a thermistor-based sensor that continuously reports the internal oven temperature to the control board. When the sensor shorts internally, its resistance collapses toward zero, causing the A/D input to read an abnormally low value and triggering this fault code.

A shorted probe is distinct from an open-circuit failure. Rather than an infinite or very high resistance reading, a short produces near-zero resistance, which the control system interprets as an impossibly extreme temperature signal. This condition prevents the oven from operating safely or accurately in any cooking mode. The relay board processes the probe's signal and compares it against expected A/D value ranges, so both the probe itself and the relay board's input circuitry are suspect when U25 appears.

The recommended diagnostic approach begins with clearing the error and running a basic cooking mode to determine if the fault is intermittent or persistent. If the error returns immediately, the upper relay board should be replaced. This sequence accounts for the possibility that a relay board input failure, rather than the probe itself, is producing the abnormally low A/D reading. Wiring harness integrity between the probe and the relay board should also be inspected for pinched or heat-damaged conductors that could create a short to ground.

Source: manufacturer service documentation.

Common causes of U25

  1. 01

    Failed ambient temperature probe (shorted thermistor)

    Part replacement

    The thermistor inside the ambient probe can develop an internal short, driving its resistance to near zero. This directly produces the low A/D value of 0x10 or below that triggers U25.

  2. 02

    Shorted or damaged probe wiring harness

    Wiring / connection

    Wires running from the ambient probe to the relay board can become pinched, melted, or abraded over time, causing a short to ground or to another conductor. Inspect the full length of the harness for heat damage, chafing, or contact with the oven cavity wall.

  3. 03

    Faulty upper relay board A/D input

    Part replacement

    The relay board processes the analog signal from the ambient probe and converts it to a digital value. If the input circuit on the relay board has failed internally, it can register a falsely low A/D reading even when the probe and wiring are intact. Replacement of the relay board is the primary corrective action called out in the diagnostic procedure.

  4. 04

    Moisture or contamination at the probe connector

    Wiring / connection

    Condensation or grease contamination at the probe's connector pins can create a low-resistance path between contacts, mimicking a shorted probe. Disconnecting and inspecting the connector for corrosion or debris is a quick check before replacing components.

  5. 05

    Intermittent connection causing a transient short

    Wiring / connection

    A loose connector or a wire that intermittently contacts a grounded surface can produce a temporary short that clears on its own but re-triggers the fault code during certain operating conditions. If the error does not return immediately after clearing, check all connectors along the probe circuit for security.

See the test procedure for each cause

Frequently asked questions about U25

What does U25 mean on a Dacor oven?
U25 means the ambient temperature probe in the upper or single oven cavity has shorted, causing the relay board's analog-to-digital converter to register a value of 0x10 or lower. This value falls outside the valid range for normal probe signals and tells the oven's control system that the temperature sensor data cannot be trusted. The oven will display this code to alert the user and prevent inaccurate or unsafe operation.
Can I reset the U25 error code and keep using my Dacor oven?
You can clear the U25 error and attempt to run a basic cooking mode to check whether the fault was intermittent. If the code returns immediately or during operation, the oven should not be used until the underlying problem is repaired, because a shorted ambient probe means the control system cannot accurately monitor oven temperature. Continuing to cook without a functioning temperature probe creates a risk of overheating.
Is it safe to use a Dacor oven that is showing a U25 error?
It is not recommended to use the oven while U25 is active. The ambient temperature probe provides the control system with critical data for regulating heat output. A shorted probe means the oven is operating without reliable temperature feedback, which could result in the oven running hotter than the selected setting without triggering a safety response. Have the probe and relay board inspected before resuming use.
How do I fix a U25 error on a Dacor oven?
Start by clearing the error code and running the oven in a basic cooking mode to see if the fault returns. If U25 comes back, inspect the wiring harness between the ambient temperature probe and the upper relay board for shorts, heat damage, or loose connectors. If the wiring checks out, the next step is replacing the upper relay board, which is the primary repair action indicated for this fault code. In some cases the ambient probe itself has shorted internally and also requires replacement.
How much does it cost to repair a Dacor oven U25 error?
Repair costs depend on which component has failed. If only a wiring harness connector needs cleaning or reseating, the cost may be limited to a service call fee, typically in the range of $75 to $150. Replacing the ambient temperature probe or the upper relay board adds parts costs that can bring the total to $200 to $500 or more depending on part pricing and labor rates in your area. Getting a diagnostic quote from a qualified technician before authorizing repairs is advisable.

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