Luxury vehicles are expensive to buy and fix, but buying used is a good way to partake without a lot of money upfront. Buying a used Audi A4 is a good choice as they are more reliable and can be modified to increase their power. However, there are a few maintenance problems common to the older used A4s that you should be aware of, such as timing belts, ignition coils, oil sludge, and wheel problems.
You should change the timing belt by around 50K miles, much ealier than normal. A broken timing belt can result in engine damage that will cost far more than replacing the belt in the first place, which is around $800 at most shops. These bad timing belts were finally fixed at the turn of the century, so A4s after that point do not have the dire timing belt replacement requirement. Find out when your used Audi was last changed, and if it has been awhile, make sure to do it soon.
You will also want to use fully synthetic oil instead of natural oil. This will help avoid one of the most common problems on used A4s: oil sludge. Oil sludge is clumps in the oil that comes from water. Like the timing belt, this can cause bad engine damage.
The control arms are notorious for going bad very early on used Audi A4s, sometimes as early as 30K miles. This is part of the ball joint of the wheel, and if it goes bad you will have to get the entire unit replaced. Again this was fixed by the 2000 A4s, so if you get a slightly later used Audi you won’t have as many problems with it.
Some other problems you may have to contend with are bad ignition coils, especially on the 1.8 engines. Bad water heaters at around 35K miles, which cause overheating due to a bad impeller shaft, again fixed on 2000 models. And on convertibles, the rear windows sometimes spring leaks, leading to an expensive roof replacement.
Keeping in mind these common problems will help you be prepared for the expenses you may face. Parts for used Audi A4s are not expensive, but the labor often is. Always have an extra couple grand on hand on top of what you pay for your A4.