GLA Hybrid GPS Navigation Problems

That sounds frustrating! I had a similar car GPS issue with my BMW 3 series. The navigation was all over the place. In my case, it turned out to be a faulty GPS antenna amplifier. It's a little box that boosts the signal from the antenna to the navigation unit. Do you know if your GLA has a separate amplifier for the antenna, or is it built into the antenna itself? If it's separate, that might be worth checking. I'm no expert, but that fixed my car electronics problem. Maybe check the antenna connection as well, it could be loose.

Thanks for the insight! I'm not entirely sure if the GLA has a separate amplifier, that's a good point. Where exactly was the amplifier located in your BMW? Knowing that might give me a clue where to start looking in my Mercedes. Also, how did you diagnose it as the amplifier and not just the antenna itself?

Okay, so in my BMW, the GPS antenna amplifier was located under the rear spoiler, near the antenna base. It was a pain to get to. As for diagnosis, a technician at the shop used a multimeter to check the voltage at the antenna connection. Apparently, there was power going to the amplifier, but no amplified signal coming out. He then bypassed the amplifier and connected the antenna directly to the nav unit and the GPS signal was good, which pointed directly to the amplifier being the issue. It might be worth getting a professional to check the car electronics, especially if you're not comfortable with car antenna repair. The faulty GPS antenna was causing me so much trouble.

Thanks a lot for the detailed explanation! That's really helpful. I took it to my trusted mechanic, and after checking the connections and voltage, they confirmed it was indeed the GPS antenna that was faulty, just like I initially suspected. Replaced the antenna, and the navigation system is now working perfectly again. The final cost was pretty much what I expected, right around 200€. Appreciate your help in narrowing down the possibilities!