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Error code reference

Dacor Oven Error Code C34

Relay board open thermistor detected (ambient temperature probe open).

Dacor codesDacor oven codes

Relay board open thermistor detected (ambient temperature probe open).

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What C34 means on a Dacor oven

The C34 error code on a Dacor oven indicates that the relay board has detected an open circuit condition in the ambient temperature thermistor. The ambient thermistor is a negative temperature coefficient (NTC) resistor mounted on or near the relay board that monitors the internal cabinet temperature surrounding the control electronics. When the thermistor circuit reads as open, the relay board loses its reference signal for ambient temperature, triggering this fault code. An open thermistor means the circuit resistance has risen to an effectively infinite level, preventing any usable temperature data from reaching the relay board.

The most common causes of this fault are a physically failed thermistor, a broken or disconnected wire in the thermistor circuit, or a corroded connector between the thermistor and the relay board. Thermistors can fail internally due to heat stress or age, causing the component itself to open. Wiring harnesses in the oven cavity environment are also susceptible to damage from heat cycling, pinching during servicing, or rodent activity. In some cases, the relay board itself may have a damaged input circuit that falsely reports an open thermistor even when the probe is functioning correctly.

Diagnosing C34 requires checking the thermistor's resistance with a multimeter and comparing it to the expected value at a known ambient temperature. A properly functioning NTC thermistor should show a measurable resistance that decreases as temperature increases. An open reading (OL or infinite resistance) on the meter confirms the thermistor has failed. Technicians should also inspect the wiring harness for breaks and verify that all connectors at the relay board are fully seated and free of corrosion before condemning the thermistor itself.

Source: manufacturer service documentation.

Common causes of C34

  1. 01

    Failed ambient thermistor

    Part replacement

    The thermistor itself has opened internally due to age or heat stress. Measuring the thermistor with a multimeter will show infinite resistance (OL) rather than a finite resistance value.

  2. 02

    Broken or damaged wiring harness

    Part replacement

    The wire connecting the ambient thermistor to the relay board may be broken, frayed, or burned through. Visually inspect the full length of the harness and use a multimeter to check for continuity.

  3. 03

    Loose or corroded connector

    Wiring / connection

    The thermistor connector at the relay board may have pulled loose or developed corrosion on its terminals, creating an open circuit. Disconnecting, inspecting, and reseating the connector can resolve this without replacing parts.

  4. 04

    Faulty relay board

    Part replacement

    If the thermistor and all wiring test correctly, the relay board's thermistor input circuit may have failed. This would require replacing the relay board to resolve the fault.

See the test procedure for each cause

Frequently asked questions about C34

What does C34 mean on a Dacor oven?
C34 on a Dacor oven means the relay board has detected an open circuit in the ambient temperature thermistor, which is the sensor that monitors temperature around the oven's electronic control components. An open circuit means the relay board is receiving no usable signal from the thermistor. The fault is most often caused by a failed thermistor, a broken wire, or a loose connector in the thermistor circuit.
Can I fix the C34 error myself?
A knowledgeable DIYer can inspect the wiring harness and check connector seating without special tools. Testing the thermistor itself requires a multimeter to measure resistance and confirm whether the component has failed. Replacing the thermistor or relay board involves working near the oven's electrical components, so the appliance should be unplugged before any inspection or repair is attempted.
Is it safe to use my Dacor oven while the C34 code is active?
It is not recommended to continue operating the oven with an active C34 fault. The ambient thermistor helps the control system monitor temperatures around the relay board electronics, and operating without that feedback could mask overheating conditions that might damage the control components. The oven should be serviced before regular use resumes.
Will resetting the oven clear the C34 error code?
Resetting the oven by cycling power may temporarily clear the C34 code, but the error will return if the underlying problem with the thermistor circuit has not been corrected. A reset does not repair a failed thermistor, broken wire, or faulty relay board. Proper diagnosis and repair of the thermistor circuit is required for a lasting fix.
How much does it cost to repair a Dacor oven C34 error?
Repair costs vary depending on what component has failed. Replacing the ambient thermistor is typically the least expensive repair, with parts costs generally in the range of $20 to $80 depending on the specific model. If the relay board requires replacement, parts costs alone can range from $150 to $400 or more. Adding professional labor typically brings the total repair cost to somewhere between $150 and $500 depending on the diagnosis and parts needed.

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