(1) Erase the set DTC.
(2) Turn on the cruise control, speed limiter, or ACC function.
(3) Check whether the DTC is set again.
Is the DTC set?
The trouble can be an intermittent malfunction (Refer to General Information - How to Use Troubleshooting/Inspection Service Points, How to Cope with Intermittent Malfunctions HOW TO COPE WITH INTERMITTENT MALFUNCTIONS).