Please can you give me your thoughts on this: The ECON light came on permanently indicating fault with AC, so i think may aswell get the gas renewed as nearly 4 years old and never been changed. The car is a A4 2005 3.0L V6 TDI S line, so take along to local garage their machine has options to set the car make model into it and it will sort out quantities of gas, oil etc itself. It thinks it needs 500g of gas. So it pulls out 820g of old gas (no more so not a leak). So the mechanic and i look in the book and it says for a A6 it can be 800g so he changes the machine manually to put 800g back. When finished ECON light still on, so he plugs in their diagnostic fault reader and it comes up with the following fault code "00819 High pressure sensor - G65 open circuit" So its concluded the sensor is faulty and needs renewing. After reading a few posts on here i find that the correct quantity of gas is labelled up on the underside of the bonnet. This reads 500g +- 20g. I assume that therefore it is over pressurised and that the sensor is working correctly. If so does anyone have ideas on why the pressure would have got so high in the first place?