I have had a Coolant Level warning pop up on my Caddy Maxi Life randomly(mostly when parked outside overnight) for about two years now.

Anyhow after talking to a VW mechanic he suggested that the sensors/prongs that are housed within the reservoir accumulate crap on them and become a pain in the arse and need to be either replaced(new tank) or the tank drained and cleaned out.

So being a lazy barstard I got in with a 1" inch brush and gave them a scrub and wallah all fixed. Just thought I'd mention it in case anyone else is having the same thing.

Two Dogs

P.S. Can't see why this would not work on other models