Too low a FG reading?

Did my 2nd all-grain and struggled with the same things I did with the 1st (crappy thermometer + problems cooling). I bought a digital therm thinking it would solve my problems, but still had issues. Batch sparging and poured in what I thought was 162F water in my mash (target of 150F). When I measured my temp showed 155, being a little high I tried to add just under 1 quart of room temp water...stirred and measured again and it said 140! I thought "that can't be right", tried several more measurements and each said 140. At this point I'm thinking something was wrong with my original temp and it wasn't really 155 at the beginning...and I cooled it way too much, so I added some 3 quarts or so of my "hot" water and measured again and it read 145...got frustrated and just closed the cooler..let it sit for 45 minutes and checked again and the temp now said 152! (this is after 45 minutes in a cooler that last time lost a lot of heat in the hour mash)

So basically I have no idea what temp I was mashing at because I have zero confidence in the thermometer I was using as it was all over the place.

Anyway, to my original question: Once I finished mash, boiled, etc...my OG was 1.041 (which was damn near right on what my target was). I'm thinking things worked out ok, I pitch my yeast and let it go. It ferments pretty strong within 24 hours and for several days. Now I just checked reading and it reads 1.002 (which is lower than the 1.010 target).

So my question is, how bad is this? I didn't think anything fermented that low? Did I actually make beer or just flavored water? Or did I just make a stronger beer than I intended? I'm not sure what that really low FG reading means to me...can someone explain it to the newb? What kindof issues would I have if I was WAY outside the required temp for mashing (either high or low)? Would beer still ensue?

All it means is that your beer is going to be a little dry. What kind of beer were you brewing?

Different temps in your mash can do different things for your beer. You probably ended up mashing around 145-149. This would give you a highly fermentable wort. This means that your yeast will get more sugar and end up fermenting a little bit more. It will leave you with a dryer beer.

If you mash around 156-158 you'll have a very malty, sweeter beer. It won't ferment quite as much. This is why most people mash right around 152-154. It gets the best of both worlds.

Thanks for the reply. I was brewing BierMuncher's centennial blonde