BMW F22 M235i xDrive - N55 engine / ZF8hp45 Automatic transmission

Hey guys, I’m having a very strange issue with my M235i which is why I’m making this post. As the title suggests, my car’s computer seems to be resetting itself every time I start the car.

I first discovered this after taking the car for emissions testing a month or two after I bought it (used 57k miles). The mechanic told me it didn’t pass because 2 emissions monitors were not ready despite passing the tailpipe test, and that I needed to drive it more. I took the car home, let it sit for a bit while I worked, and then started it up and checked the codes only to find ALL of the monitors were back to not ready (aside from those that are set to ready by default). After multiple driving cycles and scans, I realized that shortly after the car starts up the car is doing the equivalent of clearing DTC codes. It’s almost like the battery is being disconnected from the car briefly. It does retain the info memory as I can read stored faults that are non-DTC codes using bimmerlink through my MHD adapter. There were a number of faults in the info memory, but a few consistently come back immediately after clearing and starting the car, but I they are just a symptom of the problem.

Aside from preventing me from getting my emissions sticker, there is no noticeable impacts from this. As far as any other problems I’ve seen related to the electrical system, I have noticed my DRLs flicker occasionally when unlocking the car and the cruise control erratically shuts off after a while.

I have tried a number of things to fix the problem, such as changing out the battery, reflashing the tune on the car to stock using MHD incase the previous owner had a tune on it, and checked all the fuses in the front and back of the car. I really don’t want to take it to the dealer because after talking with them they didn’t seem trustworthy. I also unfortunately don’t have access to ISTA and am not sure how to securely get it. The next thing I’m thinking of doing is replacing the voltage regulator on the alternator, or just straight up replacing the alternator, starter, belt, and tensioner if that doesn’t work.

Has anyone out there heard of a similar issue or know what might be causing this?