Why does my Audi engine make a knocking noise when I start it?

I recently bought a used Audi A4 and have noticed that when I start the engine, it makes a loud knocking noise for a few seconds before going away. I'm concerned that something may be wrong with the engine. Is this a common issue with Audis?

This knocking noise is most likely caused by a worn out crankshaft position sensor. It's a common issue with Audi engines, especially in older models. I recommend taking your car to a trusted mechanic for a diagnostic test and replacing the sensor if needed.

I had a similar issue with my Audi A6 and it turned out to be a faulty fuel injector. It's best to have a professional take a look at your car to determine the exact cause of the knocking noise and fix it before it causes further damage.

I own an Audi Q5 and had the same problem when I first bought it. The knocking noise was caused by a loose exhaust manifold. I tightened it myself and the noise went away. Just be careful not to over-tighten it, as that can cause bigger problems.