I have w212 facelift 7/2013 with aftermarket NTG 4.5 installed. Untenna is is under the dash. The problem is most time it takes three minutes or more to pick satellites. Also can loose signal either during driving or after a short stop. There seems to be no pattern to it. Tried changing gps antenna and position( still think maybe that's the case). Maybe somebody knows anything or had similar problems. Thank you.

 

Do you have more than one GPS antenna ? If so then one of the antennas is interfering with the other. If you can put one on one side of the car and the other on the other side. It is also possible that a car camera could be putting out a signal that could interfere with the GPS signal. If you have a camera then disconnect it and see if the problem goes away. Other than that this is all I know.

 

Unfortunately I only have one GPS antenna and the problem was there before the camera was added

 

Sorry then, that is all that I know. If you have a good car audio store near you they should be able to trouble shoot the problem. They would be cheaper than the dealer. Good luck