Adjust the engine idle speed periodically on the engine at normal operating temperature.
To adjust the idle speed:

Engine oil and filter change
Throtile cable playSpecial tools and equipment
Recommended service material
Note
required service material is also described in the following.
“Front brake master cylinder components” “rear brake master
cylinder components” “rear brake pedal construction”
Special tool
...
Excva removal and installation
Removal
Turn the ignition switch off.
Remove the left side cowling. Refer to “exterior parts removal and
installation” in section 9d .
Connect the special tool (mode select switch) to the dealer mode
coupler. Refer to “self-diagnostic procedures” in section 1a .
After tur ...
DTC “c49” (p1656): pair control solenoid
valve circuit malfunction
Detected condition and possible cause
Detected condition
Possible cause
Pair control solenoid valve voltage is not input to ecm
Pair control solenoid valve circuit open or short.
Pair control solenoid valve malfunction.
Ecm malfunction.
...