You're on to it Paul....yep, makes very good sense...any proximity sensor should operate at ALL times the ignition is on...by definition, that's what a proximity sensor is...something to tell you of any object within close range, so you are aware. I'll look for a way of making this happen. To be honest, I'm a bit disappointed in Citroen for this....I also have a Mercedes Vito 8 person people mover, and its proximity sensors ALL work ALL the time the key is on, whether you're in neutral, park, drive, or just eating a scone. Just very jolly sensible. By the way, if any of you out there want to make your late model C5 ride better than the pogo stick pitchy ride they come with as standard, let me know.....I've experimented and got mine running pretty much as smooth and flat as my Xantia did...involves using green spheres though...