Diagnostic Procedure with Cancel Code: 21

WARNING: This page is about a different car, the 2022 Subaru WRX. However, it is still accessible from the selected car via links, so may be relevant.

Cruise control command switch malfunction is detected.

Trouble symptom:

Cruise control cannot be set. (Canceled immediately.)
Cruise control cannot be released.

Refer to 11 for diagnostic procedure. Ref. to CRUISE CONTROL (DIAGNOSTICS)>DIAGNOSTIC PROCEDURE WITH CANCEL CODE>11