Originally Posted by
jpenneck
What MMI hardware exchange are you referring to ?
There are actually two possible hardware exchanges. The first one is exchanging the cellular radio with an updated one. This exchange is currently only offered in markets where T-Mo has upgraded their network. In those markets you'll find yourself being downgraded to 2G. They did the switch here in NorCal back in September. The original radio in the 2013 units doesn't support the new frequency bands that T-Mo is moving to. The new radio supports those bands and also fully supports AT&T and the faster HSPA/HSPA+ networks. The original radio only supports the slow UMTS network. MY2014+ already come with the updated modem.
The second one is exchanging the entire 5F module with a redesigned unit. That's the entire MMI head unit with CPU, harddisk, radio, everything (you'll get updated maps for free as well). The original design has a known hardware issue, that causes it too lose and fail to reacquire the GPS signal or never acquire a signal in the first place. You may not notice this for a while, because in the absence of a GPS signal, the nav uses signals from the ECU such as speed, travel direction, steering angle etc. to approximate your current position based on the last known location. Sooner or later it will place you in a large body of water or otherwise miles away from your actual location, though. Owners who park in an underground structure have noticed this early on as the system fails to acquire the GPS signal once emerging from the underground structure. This issue dosen't affect just 2013 models. It affects all models with the MMI 3G+ up to about the first half of MY2015, when they finally figured out what's going on and redesigned the head unit.
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