Dacor Oven Error Code U21

The U21 code means the upper or single oven cavity exceeded 890°F during a self-clean cycle, triggering an over-temperature safety fault. The control board monitors the cell center temperature throughout the self-clean process and shuts things down when that limit is crossed. This code requires a service call rather than a simple user reset. Operating the self-clean feature again before the cause is identified is not recommended.

After a U21 fault, you should avoid running the self-clean cycle until a technician has inspected and cleared the oven. Normal bake and broil functions may still operate, but the root cause of the over-temperature event has not been resolved and could affect other operating modes depending on which component failed. Treat the oven as potentially unsafe for self-cleaning until it has been serviced.

Repair costs for a U21 fault will vary depending on which component has failed. A temperature sensor replacement is typically a lower-cost repair, often in the range of $100 to $250 including parts and labor. A control board replacement is more expensive, generally ranging from $300 to $600 or more depending on the specific model and labor rates in your area. A technician diagnosis call is usually required first to confirm the failed component before parts are ordered.

Dacor's guidance for U21 is to contact a qualified service technician, and that recommendation exists for good reason. The fault involves a thermal safety event, and the components that need to be evaluated, including the temperature sensor, control board relays, and interlock switches, require technical testing equipment and experience to diagnose accurately. Attempting DIY repairs without proper diagnosis risks repeated overheating or component damage.

Cycling power to the oven may clear the displayed U21 code temporarily, but it does not resolve the underlying condition that caused the over-temperature fault. If the temperature sensor, control board, or relay that caused the fault is still defective, the code will return the next time a self-clean cycle is attempted. A reset should not be treated as a fix.