Daughter's bug was hard to start once it got cold here and I dug around some members had success with replacing coolant temp sensor, others with crank sensor, and others say cracked coil with moisture inside. You need to own at least a cheap scan tool. I got a Bosch one for $29 shipped. No VAG but it actually did throw the crank code that fixed ours... I learned immensely from using it too.I parked it overnight and it got really cold and went the next day to start it and no start.