Dacor Oven Error Code L30

The L30 error code on a Dacor oven indicates that the lower oven temperature sensor (probe 1) has registered an open circuit condition. Specifically, the analog-to-digital converter monitoring the probe is reading a value of 0x3F0 or higher for a continuous period of 60 seconds. This high A/D value corresponds to an extremely high resistance reading across the sensor circuit, which the control interprets as a broken or disconnected probe rather than a valid temperature measurement. The lower oven temperature sensor is a negative temperature coefficient (NTC) or resistance temperature detector (RTD) type probe that changes resistance in a predictable pattern as oven temperature changes. When the circuit reads at or above the 0x3F0 threshold continuously, the oven control cannot confirm a valid temperature and triggers this fault to prevent unsafe operation.

The relay board plays a central role in this diagnostic because the sensor signal passes through connection points at that board before reaching the main control. A loose, corroded, or damaged connector at the relay board can introduce enough resistance into the circuit to push the A/D reading into fault territory, even if the probe itself is functioning correctly. The probe connector at the sensor end is equally important to check, as heat cycling inside the oven cavity can cause connectors to expand and contract repeatedly, eventually loosening terminal contact. Physical damage to the wiring harness between the probe and the relay board, such as chafing against sharp edges or heat-related insulation failure, can also create an intermittent or permanent open in the circuit.