Why does my Audi A4's engine make a knocking noise?

I've noticed that my Audi A4's engine has started making a knocking noise when I accelerate. What could be causing this and what should I do about it?

The knocking noise could be due to a faulty fuel injector. I recommend taking your car to a certified mechanic for a diagnostic test and potentially getting the fuel injector replaced.

The knocking noise can also be caused by low-quality fuel or dirt and debris in the fuel system. Try using a fuel system cleaner and fill up with higher quality gasoline.

I experienced a similar issue with my Audi A4 and it turned out to be a faulty timing chain tensioner. You might want to have that checked by a professional.