I bought this car used about 6 months ago. Great car. Loved everything about it. I work from home, so we don’t drive very often. I usually only put about 4000 miles on my cars per year. When I bought my car from the Porsche dealer in town, it was already Stage-1 91 tuned and had a custom intake.

I started to hear a slight tick in the engine while driving it. With a Stage 1 tune, sometimes, that can be caused by bad gas or dirty oil. I put in new gas, added some octane boost, and got an oil change, but the tick didn’t go away… it got a little better, but didn’t go away. In fact, the engine light came on, throwing a P0333 knock sensor code.

So I took it to the Audi dealership in town to have them look into it. They came back with the bad news that one of my cams were knocking and it was likely a catastrophic problem that would require a new $30k engine replacement.

I took the car to a local German vehicle specialist for a second opinion, giving them no information other than that the engine light had turned on. They found metal shavings in the oil and came to the same conclusion: the only option would be an engine replacement. They quoted $22k + 20 hrs of labor.

Turns out, this is a quietly known issue in the B9 variant, because Audi fixed it with better rocker arms in the 2019 B9.5 variant.

I bought my Audi with about 64,000 miles. I have changed the oil about every 5k miles. I have made multiple long road trips and commute a decent amount for work. One morning at about 73.000 miles, I noticed some stuttering/misfiring on a cold start. It didn't misfire enough to cause a CEL or anything like that, but you could feel it every once in a while while letting the car idle sitting in it. I also opened the hood and heard a random small knocking noise every minute or so.

I then decided to change my oil. Once I took the filter off, I set it down on a rag and continued to do the oil change. Once done, I picked up the filter off of the rag and I immediately saw an issue. There was small metal shavings sitting on the rag. I checked in between the fins of the oil filter and sure enough, there was metal shavings.

After doing some research, it seems most of model year 2018 Audi S4's have issues with the rocker arms and can lead to catastrophic engine failure and metal in your oil. This is not going to be a cheap fix and it is a mechanical issue with the motor which Audi does not seem to care about as it is a common problem. They resolved the issue with revised rocker arms for the 2019 model year. Now I am stuck with a car that could blow any minute due to mechanical failure.