[6MTZEDM2]

I recently purchased a 2021 BMW M2 Competition. Initially things were great, and I was overjoyed to own a car that I had lusted after for so long.

During the break in period the car started to get random drivetrain malfunction codes with no check engine light. The DTC code specified that it was okay to drive, but power would be cut. Since I was still in the break in period and the code would disappear after restarting the car I decided to wait until my break in service to get it looked at. Occasionally I would get a Drivetrain Malfunction accompanied by a check engine light, but they would clear themselves frequently. In the meantime, I purchased a BMW code scanner and read the error codes off the DME. The primary fault was Knock Sensor 2 “Engine noise below limit value or line disconnect”. As an Electrical Engineer, and someone who is literate, I took this as no big deal since it appears to just be a wonky sensor and nothing major.

Another detail that led me to postpone diagnoses by the dealer was the fact that some local enthusiasts heavily recommended that I stay away from BMW of San Antonio. This is a bit disappointing since I live in San Antonio Texas but having also had a bad experience with sales at that dealer, I was happy to avoid it. The closest dealer outside of SATX, which was also recommended by the local CCA group, is BMW of South Austin. Since that’s an hour and a half drive each way, I figured I would get my break in service and drivetrain malfunction situation analyzed in the same trip.

Fast forward to completing the break in period and going to my first service appointment at BMW of South Austin. They perform the break in service and then analyzed the fuel quality logs in the ECU. They informed me that the ECU was reporting that the last five fill-ups have been logged as poor-quality fuel (0 out of 5). They told me to make sure I’m filling up with premium and to change fuel station. This was a surprise to me since I typically fill up with Shell 93 octane and haven’t had issues with bad gas in the past. I also didn’t like their prognosis based on bad fuel quality since I know that the car doesn’t actually chemically analyze the quality of the fuel. Instead it relies on how much ignition timing it can run without measuring knock from the knock sensors. Obviously if the knock sensor is bad or something around it is causing it to trigger incorrectly then there will be a false reading going into that fuel quality algorithm… Anyways I played along with their prognosis since after all it sounded like they were trying to help and were going through their fault debugging process. I filled up at two different locations with 93 octane and the problem only got worse. It got to the point where I couldn’t drive the car without having a drivetrain malfunction error.

I scheduled another appointment at BMW of South Austin. I dropped off the car on a Friday afternoon and took a loaner car home. They were busy so they didn’t get to start diagnosing the car until Monday which wasn’t a big deal. They informed me on Tuesday that they would be replacing Knock Sensor #2 and were waiting for the part to arrive next day. Again, this made sense and was no problem. They installed the new sensor and did some road testing. They also drained some fuel out of the car and refueled it at their preferred location. They told me that the fuel they removed from the car was “hazy”, but that’s very vague. To me any gasoline looks “hazy” especially when not in a sealed container… Anyways, they said that they were no longer seeing issues after changing out the gas. Friday night comes around and I get a text from my service advisor asking if it’s okay for the shop foreman to drive the car home to do more road testing. Mind you they have already put 30 miles on the car, but I wasn’t going to say no to them being thorough. Unfortunately, since I was working in a building without cell service my message didn’t send until 5:30 PM which meant the service center was closed. I figured that maybe the shop foreman or someone else would take it for a drive in the morning and provide a status update. I called later Saturday morning (today) and inquired about the status of the car. My service advisor was out, but they stated that it had not been test driven again. They gave me the option to come pick up the car today since it appeared to be behaving better, or to wait until Monday to have it test driven again. Since it had been a week without the car, I decided to be optimistic and pick it up. I knew that it might not be fixed, but I figured it was worth a shot. Since Austin is a bit of a drive from San Antonio, I arrived to pick up the car right before the service center closed. Everything seemed normal initially, so I proceeded to drive home.

As I begin my drive, I notice that I’m hearing more engine noise, and especially intake noise. I started to worry that maybe they had not re-installed my intake manifold correctly… Once the car was warmed up, I started to test things out some more by adding more throttle and running through the RPMs. The car definitely sounded a little different but wasn’t throwing error codes, so I wasn’t sure what to think. About 10-15 minutes into my drive I get a drivetrain malfunction code. I was disappointed, but knew it was possible so continued on. At this point I was more concerned about the new increase in sound from the engine. Close to home I stopped for some food and decided to get my code reader out of the trunk. When I opened my trunk, I found my engine cover, the large rubber firewall / hood gasket thing, and one of the strut tower covers. I was annoyed and a bit confused to see that the car was still in pieces but proceeded to go read the codes. In the meantime, my friend with an F80 informed me that it would be normal to hear more of the engine / induction sounds without the rubber gasket installed so that was a bit of relief. When I scanned the DME I read the same code about knock sensor #2 being below its noise threshold. After scanning the codes, I got out of the car and noticed that my cowl cover was also missing except this part doesn’t appear to be in the car at all. I’m guessing it’s probably on a shop workbench.

As a new BMW owner this is very underwhelming and frustrating to say the least. I’m sharing my experience here in hopes that maybe it will help someone in the future, but also to see if the community can potentially help as well. My first question is what dealer and service advisor do people in the SATX / ATX area recommend? Maybe this is just a fluke, but I really don’t feel taken care of. Secondly, has anyone else had a similar experience with a brand new S55 and know what the problem might be? I know they replaced the sensor, but I’m not sure if they did continuity checks for the wiring. I’m also curious if something near knock sensor #2 could be causing the issue or maybe a slight intermittent hiccup in the fuel or ignition system is causing it?

If you read through my first post word vomit, thank you!