I put G12 50/50 coolant in my 2008 vw jetta months ago, now I have a leak and just to prevent from over heating I topped off 50/50 but I noticed all over the inside of the hood was white powder. Did it crystalize and cause the leak?

SOURCE: how to replace a coolant temp sensor on a 2001 vw jetta 2.0

here is a picture of where it's located on your jetta:

SOURCE: volkswagen jetta over heating

hi tammy
it could be an air lock stopping the water from circulating properly i seem to recall this problem on the older VW Derby and audi 50 (same engine) there is a small bleed screw at the highest point on the cooling system that allows you to bleed this air out youll find its location in the manual

another thing to try is put a flushing agent through the system incase there are any blockages in the radiator itself

hope this helps

SOURCE: 2001 VW Jetta Leaking Water

Th cowling let in fresh air for the heateer and defroster, Their is a drain in the bottom of the cowling or heater ductwork which allows the water to escape before going into the car. I woudl gues that the drain is stopped up..

SOURCE: 2008 vw jetta air filter

i dont know want type engine you have but this might help. its for a 07
http://forums.vwvortex.com/zerothread?id=2547554

SOURCE: How do you reset a low tire pressure warning on a 2008 Jetta?

Reset the tire pressure warning, same as you would any service issue. Insert key in ignition, hold wrench button and min button, then start engine.