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Error code reference

Dacor Oven Error Code U31

Upper/single oven temp sensor shorted probe 1

Dacor codesDacor oven codes

Upper/single oven temp sensor shorted probe 1 - A/D value of 0X0010 or lower registered for 60 continuous seconds.

First step from the service manual

Verify connections at relay board. Verify probe state at probe connector. Secure connection, replace probe, or replace harness.

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

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What U31 means on a Dacor oven

The U31 error code on a Dacor oven indicates that the upper or single oven temperature sensor probe 1 has developed a short circuit condition. Specifically, the analog-to-digital converter on the relay board has registered a value of 0x0010 or lower for 60 continuous seconds. This extremely low A/D value tells the control system that the sensor circuit resistance has collapsed, which is the electrical signature of a shorted probe or wiring path. Under normal operation, the temperature sensor (typically a resistance temperature detector) produces a predictable resistance that rises and falls with oven cavity temperature. A short drives the resistance toward zero, making the control board read an impossibly low or erratic value and triggering this fault.

The components involved in this fault path include the oven temperature probe itself, the wiring harness connecting the probe to the relay board, and the probe connector. A shorted probe usually means the internal sensing element has failed and its leads have contacted each other or the probe sheath. Connector corrosion, pinched wiring, or a harness damaged by heat exposure near the oven cavity can also create a low-resistance path that mimics a probe short at the A/D input.

Diagnosis begins at the relay board by inspecting the probe connector for secure seating, corrosion, or damaged pins. With the probe disconnected, resistance across the probe terminals should be measured and compared against the expected value for the oven temperature at the time of testing. A reading near zero ohms confirms an internally shorted probe. If the probe reads correctly in isolation, the harness itself should be inspected for chafing or pinch points that could be causing the short.

Source: manufacturer service documentation.

Common causes of U31

  1. 01

    Failed temperature probe (internal short)

    Part replacement

    The oven temperature probe's internal sensing element has shorted, causing resistance to drop near zero. Disconnecting the probe and measuring resistance across its terminals will show a value near 0 ohms rather than the expected resistance for ambient temperature.

  2. 02

    Loose or corroded probe connector

    Wiring / connection

    A loose or corroded connector at the relay board or at the probe end can create an unintended low-resistance path. Inspecting and reseating the connector, or cleaning corroded pins, may resolve the fault without replacing any parts.

  3. 03

    Damaged wiring harness

    Part replacement

    Heat exposure near the oven cavity can melt insulation and cause two wires in the harness to contact each other, creating a short. Visually inspect the harness along its full length for chafing, pinching, or melted insulation.

  4. 04

    Pinched harness at oven cavity wall

    Part replacement

    If the oven was recently serviced or the probe was repositioned, the harness may have been pinched between panels or brackets. This physical damage can short the wiring without visibly burning the insulation.

See the test procedure for each cause

Frequently asked questions about U31

What does U31 mean on a Dacor oven?
U31 means the upper or single oven temperature sensor probe 1 has been detected as shorted. The relay board's analog-to-digital converter registered a value of 0x0010 or lower for 60 consecutive seconds, indicating the sensor circuit resistance has collapsed far below normal operating range. This typically points to a failed probe, a damaged wiring harness, or a loose connector at the relay board.
Can I reset the U31 error code and keep using my Dacor oven?
A power reset may temporarily clear the U31 code, but if the underlying short condition still exists in the probe or harness, the fault will return within 60 seconds of the oven attempting to read temperature again. The oven cannot accurately regulate heat without a functioning temperature sensor, so continued use without repair is not recommended and could result in uncontrolled heating.
Is it safe to use my Dacor oven while U31 is displayed?
No, it is not safe to operate the oven while U31 is active. The temperature sensor provides the control board with the data it needs to regulate oven heat. A shorted sensor means the board cannot accurately read cavity temperature, which removes the primary safeguard against overheating. The oven should remain off until the probe, connector, or harness is inspected and repaired.
How much does it cost to fix a U31 error on a Dacor oven?
If only the probe connector needs to be reseated or cleaned, there may be no parts cost, though a service call fee typically applies. Replacing the temperature probe itself generally costs between $40 and $120 for the part, plus labor. If the wiring harness requires replacement, total repair costs including labor can range from $150 to $400 depending on the specific oven model and service rates in your area.
How do I diagnose the cause of a U31 error on my Dacor oven?
Start by checking the probe connector at the relay board for a secure fit and signs of corrosion or damaged pins. Next, disconnect the temperature probe and use a multimeter to measure resistance across the probe terminals. A reading near zero ohms confirms an internally shorted probe that needs replacement. If the probe resistance reads correctly, trace the wiring harness from the probe to the relay board and look for any areas where insulation is melted, pinched, or chafed.

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