If you can see the commands sent by NavCoder then the interface is working in terms of the echoing the Tx commands back to the PC. The issue will be with the ibus connection to the car.

Check that you are conecting to the ibus properly - can you see the car's ibus data traffic? When the ignition is on, you should observe a continual stream of ibus traffic on NavCoder.

If not, check your power, gnd and ibus connections (especially ibus) to the vehicle