[Fl_Rza_99]

I turned my car on Monday morning and got an error as I pulled out of my parking spot. Drivetrain malfunction, power reduced, take to service center... Later in the day, after work, I hooked up my obd scanner and found code 131401; vanos, exhaust, cold start. Wasn't really sure what this meant so I took my car to one of the independent shops. Got a call this afternoon and they say my timing chain/tensioner are off and will have to be replaced.... for a cost of... $5660 😨. I'm new to bmws and have had the car for a little over 4 years. Bought it with 43,000 and now I'm at 82,000. I was careful and researched what could go wrong with the n55 before I bought this car. I knew some of the common flaws, and have dealt with a few, but I didn't see this issue mentioned. Any ideas what could cause such a big problem?