Am i right in thinking that the front parking sensors do not automatically turn on unless you've activated the rears by selecting reverse (or switching them on manually with the button of course)?

Reason I ask is we just drove straight into my driveway and up to the garage and the fronts didn't activate. I guess they're not live all the time?

2004 535d M Sport UK model, if that makes any difference.

 

The Front and Back should both be on at the same time.

You should test it by putting something in the front of your car.

To make sure its not malfunctioning.

 

Tim is correct. The sensors only activate by putting the car in reverse or by pressing the button. When into a parking spot while moving forwards, I frequently use the button to activate the PDC. But do be careful as the system does not pick low obstructions such as concrete curbs, which can damage the low hanging air dam in front.

 

That is working correctly.

If you think about it, it'd be a real pain in queuing traffic if the front sensors kept coming on automatically...