Dacor Range Oven Cooktop Error Code U43

Error code U43 on a Dacor range or oven points to a fault condition on the relay board associated with the upper or single oven cavity. Specifically, the code flags either a bad connection at the S19 relay position on that board, or a failure of the relay board itself. The relay board is responsible for switching power to the oven's heating elements, including bake and broil elements, by controlling high-voltage relays based on signals from the control board. The S19 relay is one of those switching components, and when its connection becomes intermittent or fails outright, the control system detects an out-of-range condition and triggers this fault.

The most common root cause is a poor electrical connection at the S19 relay terminals or the associated wiring harness connector on the relay board. Heat cycling over time can cause connector pins to loosen, corrode, or develop high resistance, which the control system interprets as a relay fault. In some cases the relay itself fails internally, either developing an open circuit or becoming stuck in a welded-closed state. A welded relay is a safety concern because it can leave a heating element energized even when the oven is supposed to be off.

Diagnosing U43 requires a visual inspection of the relay board for burned contacts, discolored components, or damaged connector pins at the S19 position. Inspecting and reseating the wiring harness connections to the relay board is the logical first step. If connections appear sound but the code persists, the relay board itself is the likely failed component and will need replacement to restore safe and proper oven operation.