Hi New to this forum. I have a problem with my audi a4 b8 2008 2.0tdi 127k I've no heat while driving just maybe very slightly and temperature gauge stays at 0 but when idling temperature gauge goes up and I've really good heat but start driving again goes back down.. I've changed theromstat still the same and the original was checked and it was fine. There has also been a new radiator and auxiliary pump but it and still no use all pipes heat up correctly. A/C is not working but I'm told that has nothing to do with it Car just seems to cool down when driving no leaks anywhere any idea's? Thanks