[Meerdock]

I’ve got a 2021 540i and recently sent my ECU out for a Femto unlock. Everything installed smoothly and the car runs fine. No CEL, no driveability issues. I haven’t flashed a tune yet, just got the DME unlocked and reinstalled.

But ever since the reinstall, the car alarm keeps randomly going off, even when it’s locked and untouched.

Has anyone run into this? Nothing plugged into the OBD, sometimes i put the MHD flasher in and out but that’s it. It’s at the shop getting the downpipe put in… I hope it’s an easy fix and not something i have to take to the dealer. I’m under warranty for under a month left and i’m sure they’re gonna give me crap about the unlock / downpipe if i bring it in.

Thanks for any insight, im surprised the alarm doesn’t trip a code or error or send something to my phone app..

[Joe-BMW33]

Try coding the alarm to ignore the ODB port. I know there is nothing in there, but it sure sounds like the port is triggering the alarm as this is the exact behavior if you left something in there. Pretty sure this is on the Bimmercode simple menu.

[Qsilver7]

Is your alarm system’s red status LED flashing differently than norm when you initiate the alarm (aka lock the car)?

Normally, you should get a slow continuous flash which indicates the alarm has been initiated. If it gives any other type of status flashing…it can mean several things…see the info below and report back if you’re not getting a slow continuous flash when you arm the system.