Written by
Elena Navarro Appliance Repair Content SpecialistPublished September 11, 2026Updated October 20, 2026
Error codeU43 / L43
ApplianceWall Oven
Quick answer
U43 and L43 mean no zero-cross (ZC) signal was seen on the relay board of a Dacor wall oven.
Model compatibility: Dacor reuses codes across series and model years, so U43 / L43 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
No zero-cross signal seen on the relay board.
On Dacor wall ovens, U43 (upper or single oven) and L43 (lower oven) mean the relay board saw no zero-cross (ZC) signal. The manual describes it as a loss of ZC on the upper board and says this error is reversible. The entry is from the service manual for 27-inch and 30-inch single and double ovens with touch-glass control; no series is named.
Causes the manual lists
Either a bad connection on the S19 relay or a bad relay board. S19 is described as the double line break relay.
What is done about it
A technician verifies the connections at S19, secures them, and if that does not clear the code, replaces the relay board. While the code is active no functions are available, so call for service.
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.
