In order to help reduce the amount of nitrogen oxide that diesel models emit, AdBlue is used to help reduce their 'NOx' emissions. This is similar to engine oil in the sense that it needs to be kept at an exact level.
If you unsure whether or not your Audi requires AdBlue; under the hood, you may find an AdBlue fillercap under your diesel filler flap (For old models this may be in the boot).
When you start to run low on AdBlue, you will be alerted when you go below 1,500 miles until you need a top-up. If your AdBlue becomes totally depleted, the health of your engine can be negatively affected.
You can refill your AdBlue by yourself as it is a simple process. However, if you are at all unsure, contact one of our Audi centres today and we will be more than happy to help.