Noob with parking sensor woes

[Willbof]

Hi all, just joined the forum in need of a little assistance.
Got the x5 last week and tryingto work my way through all the niggly problems that come with used car buying.
Its a 2003 4.6is, what a car!
Here goes...
The rear parking sensors worked fine when I got it but the fronts didn't do anything, that didn't bother me too much but now there is just a constant beep from the rear when the PDC is activated. Occasionally it wil start working again but it's a pain in the ****. Had a listen and all 8 are clicking away, some quieter than others. I've ordered a few new sensors and was going to start changing them out 1 by 1 to see if one was faulty. Is there a reccomended scanner type thing to plug in that would tell me where the problems lie to save a little time? I've read on the web that the fronts could just be the gong under the dash so will whip that out when I get 5.
Thanks in advance!

[Horizon]

If any of the sensors are defective it will case the default single tone beeping .
Some members have had the problem, even though the sensors are clicking, I was lucky when mine faulted as the defective sensor was totally dead and wasn't clicking. The BMW scanner 1.4.0 is good for diagnostics, but doesn't always pick up sensor faults if they are not totally dead. Some more advanced equipment will show how effective each sensor is, as they may be still clicking but reading as though there is something is close up. The 1.4.0 scanners can be had for £30 ish off EBay ( Chinese copy ) but as said may not pinpoint all sensor problems, but worth having anyway, as you can code the car with a few extra options.

[Willbof]

Thanks,worth getting one of those then! Coding... that sounds complicated! I may have narrowed down the suspect just now. The PDC started working briefly so I ran round the back and put my hand infront of each sensor, all but one caused the usual beeps. The suspect made no beeps.

[X5 ALN]

Find a program called BMW INPA and a cable.

It has a parking sensor test function, and you can check the range and how effective each one it is.

I had a temperamental one for ages and didn't bother fixing it till I got the dead tone you describe, as then the whole system failed to operate.

INPA identified my dead one, and I managed to change it quite easily.

[Steamyrotter]

Navcoder also does PDC checks (on a registered version only).  Shows distance to object live.
Also the documentation shows how to make a cheap and effective interface for it..

Prob a bit cheaper and easier to understand than INPA if you are not into that sort of thing!!!

But if you want more indepth info about all your car modules then INPA def the way to go.