I am most probably over thinking it , I do have an habit of doing this on problems
I've got to remove my bm54 for an upgrade and repair in the following weeks, so the carpet and the trim in the boot will be getting removed, so I should be able to check the SLS lines from the inside with soapy water,
Bobby the car has done 145k and I think there the original bags. so you are most probably correct ,I was maybe overthinking the sensor ideal.
oh my car does have the xenons, ill have to see if I get the headlight sensor error in a near future to see if its reoccurring
plus ill jack up the car n have a look
Steve