BMW help please!!!

Ringmaster · 16-05-15, 05:41 PM

I've been trying to sort out a rear parking sensor problem on my uncle's 2001 BMW 325 auto.

When placed in reverse there was a 5 second continuous beep noise which apparently indicates a faulty sensor. On the BMW forums it was suggested to turn the ignition on, select reverse and then go and listen to each sensor. If working the sensor makes a crackling noise.

I did this, found one sensor was silent and thought I'd identified the fault. Ordered 2 sensors (one off ebay, one from Amazon) and they arrived today.

The first sensor I replaced resulted in a beep and I thought I had solved the problem, but after the initial beep after fitting it the system still does not work. The same with the second sensor.

I pulled out the plastic strip in the bumper in which all the sensors sit and saw no breaks in the wires. At this point the system started to work with beeps sounding off. I quickly replaced the strip back in the bumper and nothing works again.

When I select reverse now there is no 5 second beep to indicate a faulty sensor and the 2 new sensors crackle as expected, so they are getting power, but the system detects nothing .

Do you think the car's brain is at fault? Could disconnecting the battery for a few minutes do the trick?

Any suggestions folks? Compared to my C3 this baby is complicated.

john johnson · 16-05-15, 06:59 PM

In the rs4 you can put it on the diagnostic and it tells you which one , you can use the method you used but it's hit and miss

Sandro · 16-05-15, 07:09 PM

yes, diagnostics will tell what's the problem.. but it looks like parking ecu has gone

Ringmaster · 20-05-15, 07:10 PM

Thanks chaps....

Took it along for diagnostics which indicated all 4 sensors were faulty

Error codes were cleared, the system still didn't work and no new error codes appeared

Will look at it again on the weekend.

Ringmaster · 23-05-15, 02:10 PM

Yep, looks like Sandro was right, seems ecu is the culprit......

Not sure if I can just swap in another ecu in case it is not set up for on board computer.

Cheaper option may be to fit an after market system. Hopefully can find one which will fit existing holes....

Ringmaster · 06-06-15, 07:43 PM

Another ECU didn't work. The system would only work if I plugged/unplugged the wiring from the new sensor, but as soon as I selected reverse again I was back to square one!!

I was about to give up and fit an aftermarket kit, as they are fairly cheap, but I decided to just swap around the new sensor with the sensor next to it and hey presto, it all works!

I don't get it!

16-05-15, 06:59 PM	#2
john johnson Moderator of sausages Classic Audi Club Member Join Date: Sep 2008 Location: sheffield Posts: 13,331	In the rs4 you can put it on the diagnostic and it tells you which one , you can use the method you used but it's hit and miss __________________ Mr OCD http://s159.photobucket.com/albums/t144/jsquatts/ Daily rs4 b7 with buckets that play havoc with my piles And if you are reading this as James may would say ' you're a cock '

16-05-15, 07:09 PM	#3
Sandro Grown up member Join Date: Feb 2011 Location: Chelmsford Posts: 651	yes, diagnostics will tell what's the problem.. but it looks like parking ecu has gone

20-05-15, 07:10 PM	#4
Ringmaster Senior Member Classic Audi Club Member Join Date: Apr 2008 Posts: 1,326	Thanks chaps.... Took it along for diagnostics which indicated all 4 sensors were faulty Error codes were cleared, the system still didn't work and no new error codes appeared Will look at it again on the weekend.

23-05-15, 02:10 PM	#5
Ringmaster Senior Member Classic Audi Club Member Join Date: Apr 2008 Posts: 1,326	Yep, looks like Sandro was right, seems ecu is the culprit...... Not sure if I can just swap in another ecu in case it is not set up for on board computer. Cheaper option may be to fit an after market system. Hopefully can find one which will fit existing holes....

06-06-15, 07:43 PM	#6
Ringmaster Senior Member Classic Audi Club Member Join Date: Apr 2008 Posts: 1,326	Another ECU didn't work. The system would only work if I plugged/unplugged the wiring from the new sensor, but as soon as I selected reverse again I was back to square one!! I was about to give up and fit an aftermarket kit, as they are fairly cheap, but I decided to just swap around the new sensor with the sensor next to it and hey presto, it all works! I don't get it!