Diagnostic Procedure with Cancel Code: 31
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.
Malfunction related to engine speed signal is detected.
Abnormal increase of engine speed is detected.
Gear is placed in 1st or Reverse position.
Drive with the gear in 2nd position or higher, and perform the cruise setting again. It is normal if the cancel code is not detected.