As per my title.

I removed the rear seats from my F57 JCW, but that only comes to 30 lbs on my scale.

I've read that folks often also remove the seatbelts and retracting hardware, which is quite heavy.
- But how do you stop the ecu from throwing a warning code?

My mechanic said something about adding resistors, and / or maybe Esys or Bimmer coding, but he wasn't sure.