Kenmore Range Error Code 21

Error code 21 on a Kenmore range indicates a LIN (Local Interconnect Network) communication error between the Electronic Surface Element Control board and the User Interface Board. The fault is triggered when the control system detects either no communication or a shorted condition on the LIN bus. The range will not operate normally until the underlying communication failure is resolved.

A power reset by cutting power at the breaker for a few minutes may temporarily clear the error if the communication disruption was caused by a transient voltage event. However, if there is a physical fault such as a loose connector, damaged wiring, or a failed board, the error code 21 will return after the reset. A reset alone is not a repair.

If the fix is simply reseating a loose connector, there may be no parts cost, though a service call can range from $75 to $150 for labor. If a wiring harness needs replacement, parts and labor combined typically range from $100 to $250. Board replacements, either the UIB or the ESEC, can bring total repair costs to a range of $200 to $450 or more depending on parts availability and labor rates.

Start by inspecting the LIN bus harness at the P9 connector on the ESEC-UIB and confirm it is fully seated and undamaged. If the connector looks good, trace the harness for any pinched, broken, or burned wiring. If the wiring is intact, testing or replacing the UIB or ESEC board may be necessary to resolve the fault.

It is not recommended to continue using the range while this error is active. A LIN bus fault means the control boards cannot communicate reliably, which could result in surface elements not responding correctly to commands. Discontinue use until the communication fault has been diagnosed and repaired.