Written by
Lena Hartwell Appliance Care EditorPublished October 27, 2026
VERIFIED
Error codeC78
ApplianceWall Oven
The code
Dacor labels C78 as LIGHT. It signals that the voltage supplying the display is under 15 V, and the manual names the LED board and the logic board as the possible sources.
Behavior
The error appears once the wrong voltage has been detected for 3 seconds. No functions are available while it shows, though it is reversible. The owner’s part is to call for service.
Ovens covered
Touch-glass single and double wall ovens, 27 and 30 inch, in the Dacor Wall Oven Service Manual. The series is not stated.
Repair order
The manual replaces the LED board first. If the fault remains, the logic board is replaced next. Both steps are for a technician.
Related codes
C77 and C76: the configuration errors from the same table.
Request Dacor wall oven repair on (415) 687-5926. Give the code, the model number and whether the keys are lit, so the call starts with the facts. We work in San Francisco and around the Bay.
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, from the LED board or logic board.
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.
You submit a request with your appliance model and symptom, we confirm an appointment window, and a technician performs an on-site diagnosis. You then receive a clear estimate and decide whether to proceed before any repair begins.
Yes. We provide an upfront estimate after diagnosis. No parts are ordered or installed until you approve the work, so there are no surprise charges.
Replacement parts are selected for the exact model and confirmed with you before ordering or installation.
Service areas are listed on the Locations page. Contact us with your ZIP code to confirm current coverage for your address.
Ready to get your Dacor appliance working again?
Book a repair online or call us — clear estimates and approval before any repair work begins.
