This is a very common misunderstanding. Your GPS
app may require data coverage (depends on the app). The GPS
receiver, however, does not. The receiver and the app are 2 distinct and separate entitites though many people seem to lump them together. All your receiver does is determine your current location using the GPS satellites and all it provides latitude and longitude. Everything else (maps, points of interest, routing, directions, voice prompts, etc) comes from your GPS app.
If all GPS receivers always required data coverage then the standalone GPS units would be worthless. Many of them aren't even data capable.
WiFi isn't relevant. If you're using WiFi to determine your location then you aren't using GPS. WiFi can help if your app needs data to operate and it's the only option for data.
This is why comments such as "I downloaded the latest Google Maps and now my GPS doesn't work/isn't accurate/etc" don't make any sense. Updating Google Maps has no effect on the GPS receiver itself. It's a falsely assumed causal relationship where there isn't one. If there's a problem in such cases it's coincidental. GPS Status is useful for troubleshooting such situations and for resetting the aGPS data. I've needed the latter on a number of occasions.
I have been using my GPS and ran into a bad signal area and my GPS quit working on me before.
Download GPS Status or a similar app. Next time this happens, run GPS Status and you'll see that your receiver is able to determine your latitude and longitude just fine without data coverage. It's your GPS app that gave out on you.
