For Power Commander 5 and 6 modules. Fits HD LAN (CAN-bus) models. These are equipped with a 6-pin OBD (On Board Diagnostic) port plug. In combination with this optional Auto Tune system the map for the Power Commander is automatically written; during riding. With the Auto Tune connected the rider can specify what Air/Fuel ratio (how rich or lean the mixture) should be; at each specific RPM and throttle position and/or gear selection; for the individual cylinders. Base settings are supplied. This enables to fully tune for good fuel efficiency during cruising and best power output at more open throttle positions. The Auto Tune is equipped with two Wide Band O2 sensors; which are included in the system. Wide Band sensors are more expensive than the standard narrow band sensors that H-D uses; but work much better; especially in quick changing throttle settings and will give superior tuning results.Fitment note O2 sensors: Kits come with 18mm wide band sensors; to replace the lesser quality OEM narrow band sensors. All kits include 18mm weld-on O2 sensor bungs. Late model exhaust systems; with 12mm O2 sensors; will require the use of these weld-on bungs to convert to the 18mm wide band sensors. Earlier models; with exhaust systems equipped with 18mm O2 sensor ports; will not require the included weld-on bungs. 01-06 bikes; that originally were not equipped with O2 sensors / O2 ports will; obviously; also require the 18mm weld-on O2 sensor bungs. Fitment note 4-pin or 6-pin p