Written by
Elena Navarro Appliance Repair Content SpecialistPublished September 11, 2026Updated October 20, 2026
Error codeU42 / L42
ApplianceWall Oven
Quick answer
U42 and L42 report an E2 checksum failure on the relay board of Dacor wall ovens.
Model compatibility: Dacor reuses codes across series and model years, so U42 / L42 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
Relay board E2 checksum failure.
U42 on an upper or single Dacor wall oven, or L42 on a lower one, is an E2 checksum failure on the relay board. The calculated E2 checksum does not agree with the stored E2 checksum. The service manual that lists it covers 27-inch and 30-inch single and double ovens with touch-glass control, with no series named.
How the oven checks itself
On power-up the control recalculates the checksum 5 times before it gives up and defaults to a fatal error. If the power-up test passes, the checksum keeps being monitored while the oven runs.
Result and fix
No functions are available. The manual names a bad relay board as the source and replacement of that board as the solution, so the next step is to call for service.
For a U42 or L42 in Los Angeles, call (310) 742-1907 and ask for Dacor oven repair. Mention the code, the model number and whether the code returned after the oven was powered up again.
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.
