Volkswagen: VW Coolant Light, coolant temp, coolant

Question
I bought a used 2001 VW Beetle 2 weeks ago. When I start car, a blue coolant light comes on, which seems to be normal. It goes out after a few minutes, but after driving 30 minutes the blue light comes back on and flashes. I took it to the dealer and he could find nothing wrong, but of course they didn't drive it 30 minutes as I do each day. Can you help diagnose this for me?
Thanks

Answer
the blue light indicates coolant is not warmed up, it may need a new coolant temp sensor fitting. try driving the car and taking it to the dealer while the light is on. (if needed take your partner and leave the car running in the car park so the light doesn't re-set)