Written by
Lena Hartwell Appliance Care EditorPublished October 27, 2026
VERIFIED
Error codeU23 / L23
ApplianceWall Oven
What the oven does on U23 or L23
The relay board thermistor has registered ambient above 80°C and the display reads OVER TEMP. U23 refers to the upper or single oven and L23 to the lower one. The oven shuts itself down, and the cooling fans go to high speed until ambient drops to 50°C.
The five-excursion rule
Normal function returns after the oven cools to room temperature. Only five excursions are tolerated; one more and a permanent error occurs, the oven locks out, and service is the only way back.
Owner steps in the manual
Report the occurrence by calling the customer service line.
Let the oven come down to room temperature.
Look at three airflow points for obstructions: the exhaust area, the opening along the bottom of the door and the grill across the top front of the oven.
Resume by pressing any key.
Conditions behind it
The manual points to extreme ambient conditions, meaning high heat and high humidity, and to blocked airflow. If the error stays, a technician checks for a bad relay board thermistor by running the oven in a normal mode.
Series
Dacor 27 and 30 inch single and double wall ovens.
If U23 or L23 keeps coming back, call (415) 687-5926 about Dacor wall oven repair in San Francisco. Keep a count of how often it has appeared and have the model number nearby.
Model compatibility: Dacor reuses codes across series and model years, so U23 / L23 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
U23 (upper/single) or L23 (lower) means the relay board thermistor read ambient above 80 C and the oven shut down.
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.
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Replacement parts are selected for the exact model and confirmed with you before ordering or installation.
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