Just thought I would post up my experience with my BMW E60 535. I have been having an issue for weeks trying to find out why my TPMS inactive light was on. After having my local tire shop scan my wheels and confirm the sensors were OK I found that my control unit in the trunk under the spare had water damage. Come to find out this is common on the e60 getting water in the spare tire well. So you may want to check that area once in a while to avoid an expensive fix.