I was considering Fitcamz for my 991. After reviewing comments on the Rennlist forums about Nav problems I decided to contact the company direct. I assumed with all the complaints they would have made internals modifications to correct this issue.
Comments from Fitcamx:
Hello,
Dash Cam Interference With Navigation systemsIt should be cable issue. This issue can be solved by replace the cable.
Best regards,Xyla
FITCAMX Support Team

My reply:
Your answer is not acceptable, if this is an issue you should upgrade all the units from the factory for the Porsche 991.Don't think I will purchase a product with a known defect. Your company's customer care / services need serious attention.

However, thanks for your prompt answer

 

I'd wonder if it's a problem with the Porsche wiring for the GPS antenna, one that might not be present in other vehicles, and one Porsche didn't implement because they know there won't be anything from Porsche ever being close enough to cause problems. Though I can't remember if Porsche passes just antenna signals down to the PCM or if the module collects the position itself and just passes data on the CAN bus. If it's the latter, and the Porsche module does all the work, then the Porsche cabling seems less-likely to be at risk of interference. Either way the frequency of it happening says this is a problem that Fitcam should have a better handle on addressing.