Written by
Elena Navarro Appliance Repair Content SpecialistPublished September 11, 2026Updated October 20, 2026
Error codeC78
ApplianceWall Oven
Quick answer
C78 means the display voltage dropped below 15 V, a fault tied to the LED board or the logic board.
Model compatibility: Dacor reuses codes across series and model years, so C78 may mean something different on another appliance or generation. Confirm this against your model’s documentation and record your full model number before acting.
Plain language
What this code means
Light error: display voltage dropped below 15 V (LED board or logic board).
C78 LIGHT on a Dacor wall oven means the display voltage has dropped below 15 V. The manual names a bad LED board or a bad logic board as the sources.
Ovens
Dacor 27-inch and 30-inch single and double wall ovens with touch-glass control; the series is not named.
What the oven does
The error appears after 3 seconds of incorrect voltage detection. No functions are available, and the error is reversible.
Owner step
Call for service. The manual’s fix runs in order: replace the LED board, and if that does not help, replace the logic board. That is technician work.
Important safety warning. Do not attempt repairs involving electrical components, gas, water lines, refrigerant or sealed systems. Unplug the appliance if it is safe to reach the outlet, and leave internal diagnostics to a qualified technician.
Seeing this code on your Dacor appliance?
Book a specialist visit for a clear estimate and approval before any repair.
