2016 F250 Navigation Fault after swap of Sync2 to Sync3 module

A couple of weeks ago, I swapped out the Sync2 module in our 2016 F250 with a Sync3 from eBay (China). Everything appears to be working except that I get a “Navigation Fault” almost every time I start the vehicle. After about 5 seconds, I can see the map load, and navigation appears to work fine. The unit came pre-loaded with build 3.4.23188, so I haven’t used the Cyan updater.

At the seller’s suggestion, I’ve tried a master reset and also tried adjusting the location of the GPS antenna. Even placing the antenna outside the vehicle doesn’t seem to make a difference. I also tried another antenna from Amazon ( Amazon.com ), but it doesn’t appear to work any better or worse than the one included with the unit.

I noticed on another thread that downgrading the build version might help. Has anyone tried that and had success clearing the Navigation Fault error? I’ve seen other threads claiming different antennas fixed the issue, but it doesn’t seem like a reliable solution.


SYNC Region: NA

Navigation Variant: Nav 2 24

Manufacturer Year: Unknown

Install Type: Replica

Old SYNC Version: 3.4.23188?

New SYNC Version: 3.4.23188

Do you have a error message, if so what is it?
Navigation Fault

Update Method: Unknown