Putting the gear into reverse, the parktronic's solid beep noise, which normally denotes close proximity to an object goes off, despite there being nothing behind the car. I am wondering what could be the cause of the malfunction. I am going to take it for a wash tomorrow in hopes that it's just dirty or there's just frozen water on one of the sensors.

Have any of you had this problem?

Yep happened to me loads of times.

Only really any good for close proximity parking on an even level :banghead:

As our driveway is on a partial incline it seems to start with a bleep and then once I am sure its clear anad start reversing it sort of resets itself.

Crud on the sensors could be a problem also.

Trick is not to rely on it too much and really only use it for tight spaces etc.

The new PDC on the 5 series, etc is really good with the corner/front/back sensors and it shows up on a screen and is colour coded depending on how close and object is.