Rear parking sensors - E46 M3

[Andrew Coates]

Morning guys

The rear parking sensors on my E46 M3 have developed a fault recently.

When I select reverse, the beeping tone sounds continuously for about 5 seconds and then stops, but as I get close to an obstacle, there is no sound from the sensors to warn of impending doom!

Has anybody had similar symptoms and, if so, what might the problem be.

Any help would be much appreciated.

Thanks

[Crusoe]

If you get someone to put it in reverse and hold the clutch in you should be able to get out and hear the clicking of the individual sensors. Probably one of them is not working and needs replaced. The diagnostic reader should also be able to tell you where the error is. Try making sure they are all clean first too.

[mat205125]

Have you tried giving the sensors a wipe? Mine gives some funny "readings" when the car is dirty, however in fairness only when it is absolutely filthy.

[sjj84]

Mine stopped working at the weekend, needs a new control unit. Mine however makes no noises at all and when in reverse no clicking from the sensors.

[Andrew Coates]

Tested them and they all seem to be clicking when I pass my hand across the sensor.

Anybody know where the control unit is and how much a new one is?

I assume it will be a BMW only part?

Any help appreciated.

[LockMonster]

Mine have just stopped. Sure it's all the salt and grit they put down !!

[thehos]

to op, same as mine, took it to bmw for a quote, only one of mine were faulty

[NickXX]

To the OP - my 330 did this (continuous beep).

Move the ignition into the position just before starting the car (I.e. don't start the car). Then move the gearstick into reverse.

Listen to each of the 4 sensors in turn - the one that isn't clicking or clicking very quietly is the duff one.

[Davidonly]

Mine work 100% when dry. If driven for a good while in the wet the tone sounds continuously when R engaged. Work ok the next day? Obviously water ingress....Have a warranty bu have not bothered to report it yet. Sort of hope it goes US completely actually, then it can be fixed!

[ghibbett]

Davidonly said:

Mine work 100% when dry. If driven for a good while in the wet the tone sounds continuously when R engaged. Work ok the next day? Obviously water ingress....Have a warranty bu have not bothered to report it yet. Sort of hope it goes US completely actually, then it can be fixed!

Mine do this also. Any update?

[Andrew Coates]

Thanks for all the advice guys.

At the moment, they seem to working fine. I haven't actually done anything to them other than keeping them clean, so may be that was the problem all along, or it may be just one of those little faults that keep coming and going for no reason!

[THE FERRET]

Keeping them clean may have been your problem - you haven't jet washed the car at all have you? The pressure of the water can knacker the sensors. It happened on a mate 320 a while back.