:help: how to calibrate GPS signal on WINCE 6 with Igo Primo 9

Dear community

I have a wince 6 that runs Igo Primo and want to calibrate the GPS signal.
When driving the car, the in dash system show me the car 10/15 meters left of my real position.
When I go to the GPS MONITOR APP I have all the available satellites bars with signal strenght very good.

Any hint?

Thank you.