BMW 3 Series Touring - Parking sensors on the blink - CMP

Hi,

When I engage reverse my parking sensors start beeping indicating that I am close to hitting an object, this happens even when it is clear. this is an inconsistent problem as 1 in 3 times it works fine. My local BMW dealer has ran it through their diagnostics however everything indicates it is working normally. the next step they have suggested is to remove the bumper and take a look. Before I commit to paying their labour rates for doing this does anyone have any ideas as to what it can be? I have done the obvious of checking the sensors are clean..this is a really annoying problem! Car is '04 with 85000 miles on the clock.

Thanks in advance!

BMW 3 Series Touring - Parking sensors on the blink - elekie&a/c doctor

Erratic operation of parking sensors on these is not uncommon.However,as you have found out, a diagnostic check does not always reveal the fault.It is very possibly one of the sensors in trouble.Did the dealer do a live data test on sensor operation to check distance values?as there may be discrepancies here.Also does the car have front sensors?Any fault on these will cause a problem with the rears.Not too sure if removing bumper is going to reveal much other than condition of wiring,which is generally fairly good on these.hth

BMW 3 Series Touring - Parking sensors on the blink - CMP

Thanks for the advice, I will check with the dealer.

I have just rear sensors only which should reduce the potential areas for problems..

BMW 3 Series Touring - Parking sensors on the blink - madf

One sensor may be faulty (there are four I believe)...

BMW 3 Series Touring - Parking sensors on the blink - CMP

Thanks madf - you were correct one was faulty.

I took the car to an independent specialist BMW garage for a 2nd opinion, they found and replaced one of the faulty sensors. They also managed to fix 3 other non related problems where the main dealer had told me that they could not be fixed but had to replace items, so have saved a lot of money too.