Parking sensors

I have a 2002 320DSE fitted with parking sensors at the rear. Now when I engage reverse gear I get a constant tone when there's nothing behind the car and I'm told that this probably means that one of the
sensors is faulty.
I believe I can test the sensors one by one by disconnecting them in turn and engaging reverse gear. Can anyone comment on this? Also can anyone explain how to actually remove the sensors? Does the bumper need to be removed?
Thanks
Jim
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Goffer wrote:

Probably.
Not familiar with your model - but on other BMW models with PDC, if one fails - the system fails. If one fails open - the system fails, meaning disconnecting it won't do a thing. The test that will tell you which one it is - the dealers GT1 can monitor the output from each one. Or you could buy one new one and try swapping it into each position until the fault is fixed.
Dunno how it is removed on your 3 - on a 5 series of that era, they are in the extra bumper strip - and just that strip has to be removed.

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Thanks for the prompt response.
There is a black bumper strip but when I remove it I find that the sensors are set into the bumper. I can turn them very slightly from side to side but can see no obvious way to remove them. Can anyone offer advice?
Thanks
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They usually clip in so you need to get to the back to press in the clips to release them.
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As Goffer said, a dealership can plug the GT1 into the vehicle and see exactly what the sensors are monitoring.
Another thing worth looking at is does it have any accessories that could give false readings, for example towbar, etc.

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You can hear the sensors clicking when they are working.

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Jim wrote:

You must have wonderful ears since they're ultrasonic devices..
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However, when mine packed up on my E38 it was a relay - after the dealer tried to sell me 2 x control units and 500 of labour - final bill was 80 and a loan car for a week till they fixed it - why? they screwed up by not touching the car when I left it to be fixed so I got the sales manager's M5 for a week.
Nice people to do business with. (sometimes)
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No, you can hear the pop when they start emitting. You can't hear the ultrasonic tone, but you can hear a click. --scott
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On 6 Nov, 03:03, snipped-for-privacy@panix.com (Scott Dorsey) wrote:

Had the same problem on my e46 coupe. YES you can hear the click when in reverse so it is possible to detect which one is faulty. To get them out you need to lie on the ground and reach up behind the bumper to pop them out.
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Ranger wrote:

Laying behind the car while it's in reverse isn't something I think I want to try.. call me wacky..
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Or something is stuck over it?????
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