my 2017 lexus nx factory nav map is off course, shows that am driving on water does anyone know how reset the nav ? any help appreciated

 

By any chance do you have a dash cam? I had the same problem and it turned out that the dash cam was causing interference.

 

Could also be if you are driving on a "new road" that wasn't there when the car was bought in 2017. The MAPS are based on the roads that existed at that time of the update.
I have a 2017 GS350 as well and when I was driving on a new highway "off ramp" interchange that was built recently, the NAV showed my car flying through the air.

 

My previous Ford Escape would do that, It would show I was one street over from the road I was on, Never could figure out what caused it.

 

There could be an connection issue with the GPS antenna, have the dealer check it out.

 

Have you updated the maps? If so, there's a possibility that could be the problem. In general some older GPS devices are not as accurate down to the yard/meter as more current devices. If you are attempting to use a current map set with an older device there could be syncing issues. I don't know if Lexus suffers from this kind of issue, but my old Audi did. Switching back in the Audi was easy - just swap out for the old DVDs. I'm relatively new to this generation Lexus. Are the maps on flash drive? Can you revert easily?

 

Maps are on a micro SD card, super easy to install. I did mine while driving home from the dealership after buying the updated map just a few weeks ago