I have a 1998 VW Jetta. A few months ago the temperature light began blinking intermitently. However, the temperature gauge did not show any movement. The light began to blink with more regularity and I noticed I was getting less and less heat coming out of the vents when I had the heat turned on. But still the temperature gauge stayed steady at 180 degrees (where it's always been). Then a week or two ago the temperature gauge suddenly started to rise. I can drive for about four or five miles before the gauge starts to creep towards 230 degrees and up. I'm wondering if anyone has an idea of what the main cause might be as well as how much it might cost, so I can be appropriately prepared when I take it in. Thanks for any input.