ng4 Car shown reversed on map

I’ve a problem with NG4 in my Citroen C5 Tourer 2011. GPS positioning is working fine, but it computes azimuth 180° rotated (eg. if I drive to north, navi – the arrow representing direction of my car – is showing my car facing south and it looks like I drive backwards; when navigating it tells me to turn around). I don’t know the algorithm for computing the azimuth and which sensors it uses. The car has replaced engine – maybe someone rotated the car after plugging the battery off. Can this cause the problem?

I tried to update firmware – now I have N42b and also restart the unit by pressing 1 + 5 + 3 buttons, but the problem is still the same. Any help would be much appreciated – my Citroen dealer still doesn’t know, how to fix it .

Any help would be appreciated...

Thank you and have a nice day,

Daniel