(1) Erase the set DTC.
(2) Change the power supply mode of the electric motor switch to ON (READY indicator: ON).
(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).