E46 330D parking sensors - One long beep

[anonymous-user]

Yesterday evening my parking sensors worked as they should, hooting more frequently as I reversed up the drive towards the car already on there.

Today I was shoe-horning the car into a space up the hill in Clifton, Bristol. The parking sensors just emitted one long beeeeeeeep for about 5 seconds and then stopped working.

I turned the car off, got out, cleaned the sensors with a water bottle and a rag, got back in, turned it back on...

Once again I turned it on, plopped it into reverse and the 5 second beeeep came and then nothing else, regardless of how close I got to the van behind.

Any ideas what could be wrong guys?

[anonymous-user]

Sorry, I was hasty, Just had an internet search and will be raiding the scrappy on Saturday (YESSS!)

Little clicky test is something to do tonight...

[stevesuk]

I think the one long beep is the car's way of telling you that there's a system fault.

Probably a sensor that's broken (or a break in the wiring somewhere).

From memory, if you leave it with the key in the ignition and "alive" (but obviously not with the engine on!), and with the car in reverse, if you wander round to the rear, the working sensors will emit a quiet clicking/ticking noise as they're activated.

So if one isn't making any noise, its probably that sensor that needs replacing.

I had the problem on my old car, and it turned out to be the wiring to the sensor that had a break in it. Soldering iron and some insulation tape, and all was fine until I sold the car a year or so later.

Edited to add: Ahh, you replied as I was typing Yes, the clicking noise is the thing to check first

[anonymous-user]

As for removing sensors, it is just a case of pushing the bloody things out?

fred

[stevesuk]

coombsfh said:

As for removing sensors, it is just a case of pushing the bloody things out?

fred

Hmmm, can't remember, it was a few years back. I have a feeling if you look from underneath the bumper, it become obvious. Possibly they're clipped in from behind? If you're fortunate enough for it to be one of the easy to get at ones, you don't need to drop the bumper. But I seem to recall when I looked at mine, that there are couple you can't access so easily.

Someone else probably knows and will come along and say so soon.

[_bryan_]

Just pull the black trim that they are in off the bumper. Then the sensors unclip from behind it, it's quite obvious once you've got the trim off.

[dr_gn]

...and don't waste your time with scrap ones - they're only £20 brand new off EBay (identical to a Land Rover Discovery III IIRC).

I bought 3 for mine recently - straight swap apart from having to remove a tiny bit of plastic so that the plug fits.

[anonymous-user]

Thanks for all th advice.

I have listened to the sensors and all of them tick at the same volume. Furthermore, they work very early in the morning once or twice and then resume the single 5-second hoot followed by not working.

Any ideas as to what it could be now all of the sensors (using the listenig test) seem to be ok?

Would it be prudent to buy one and replace each existing one with the new'un until the faulty one is identified?

[DJC]

coombsfh said:

Thanks for all th advice.

I have listened to the sensors and all of them tick at the same volume. Furthermore, they work very early in the morning once or twice and then resume the single 5-second hoot followed by not working.

Any ideas as to what it could be now all of the sensors (using the listenig test) seem to be ok?

Would it be prudent to buy one and replace each existing one with the new'un until the faulty one is identified?

Wait until you put it in reverse and you get the long beep; switch the engine off keeping the car in reverse; jump out and do the clicky test then.

The fault is clearly intermittent so you'll need to wait until the fault occurs before you can test it.

Removing the sensor is fairly straight forward; you need to pop out the plastic strip. It's very tough plastic but can still be marked so use a flat head screwdriver or tack remover with a microfibre cloth over the top. Pop out the top clips first, then get underneath the car and pop out the bottom strips. It's much easier with two people to stop the top clips going back into place when you remove the bottom strips!

Once the strip is out, you can unplug the individual sensor and then push the sensor out with your thumb. They sit very tight into the holder so don’t be afraid to use some force!

[nobrakelights]

Thanks for this thread, mine have been playing up for a while - intermittent too!

[dr_gn]

coombsfh said:

Thanks for all th advice.

I have listened to the sensors and all of them tick at the same volume. Furthermore, they work very early in the morning once or twice and then resume the single 5-second hoot followed by not working.

Any ideas as to what it could be now all of the sensors (using the listenig test) seem to be ok?

Would it be prudent to buy one and replace each existing one with the new'un until the faulty one is identified?

All 4 of mine ticked under test, but only one worked in practice.

[anonymous-user]

Thanks for all this help guys. I have no need to move the car today. I am being a jubilee sloth and fantasising about putting modern, reliable diesel engines into old classic barges. Also been brushing the dog and quaffing tes like there is no tomorrow.

The sensors worked beautifully last night both at the beginning (as I reversed towards an Audi A8L and an Evoque) and when I got home (reversing up the hyper steep drive at mine - nicknamed "the lifeboat house" as the drive is like a launch ramp).

kind thanks,

fred

[anonymous-user]

The plot thickens.

The sensors seem to have healed themselves. I cleaned the bugger the other day but paid no special attention to the sensors. I can now describe this problem as sporadic I think.

Will see if it does it again today - usually don't work after a long, warm day (which we are in no danger of experiencing today)or a considerable drive. However after an hour on the road today they were fine.

[dr_gn]

coombsfh said:

The plot thickens.

The sensors seem to have healed themselves. I cleaned the bugger the other day but paid no special attention to the sensors. I can now describe this problem as sporadic I think.

Will see if it does it again today - usually don't work after a long, warm day (which we are in no danger of experiencing today)or a considerable drive. However after an hour on the road today they were fine.

The thing is - you don't want to find out you've got a dodgy sensor by reversing into someone's car...FWIW I'd check further to see if you can diagnose a faulty control unit or sensor, replace it and be done with it.

[fjord]

Im keeping tabs on this. My new e46 320d does the same thing, except they have never worked.

I put it in reverse and they beep for 5 seconds as described. If i then put it into reverse again, i get no noise until i turn the ignition off, then on again. The first time i engage reverse i get the long beep, but nothing after until i turn off and then back on again.

[Mr-B]

fjord said:

Im keeping tabs on this. My new e46 320d does the same thing, except they have never worked.

I put it in reverse and they beep for 5 seconds as described. If i then put it into reverse again, i get no noise until i turn the ignition off, then on again. The first time i engage reverse i get the long beep, but nothing after until i turn off and then back on again.

I have an identical problem. Been like it for years, can't be @rsed to fix it seeing as BMW wanted something like £200 to replace one sensor, assuming that is the fault. The previous owner said it started playing up after it came back from a service by BMW Possibly as a result of the work experience kid blasting the sensors with a high pressure jet or something equally daft??

I don't get any clicks from any of the sensors when I test them but obviously the long beep is saying that there is a fault somewhere in the system, possibly loose wiring/earth? Problem with PDC faults is that it can be a number of things and can eat hours of time to get nowhere that's what's put me off.

[fjord]

Mr-B said:

I have an identical problem. Been like it for years, can't be @rsed to fix it seeing as BMW wanted something like £200 to replace one sensor, assuming that is the fault. The previous owner said it started playing up after it came back from a service by BMW Possibly as a result of the work experience kid blasting the sensors with a high pressure jet or something equally daft??

I don't get any clicks from any of the sensors when I test them but obviously the long beep is saying that there is a fault somewhere in the system, possibly loose wiring/earth? Problem with PDC faults is that it can be a number of things and can eat hours of time to get nowhere that's what's put me off.

Im crap at parking, and with the Saloon, its hard to gauge where the back of the car is in my opinion.

Anyway, i did the click test and have found 2 not clicking. One clicks loudly and the other clicks a bit quiet.

I've just ordered two sensors from ebay (from Latvia) at £25 each. I'll fit them because it's an easy job. If that fails then stuff it.

[Mr-B]

fjord said:

Im crap at parking, and with the Saloon, its hard to gauge where the back of the car is in my opinion.

Anyway, i did the click test and have found 2 not clicking. One clicks loudly and the other clicks a bit quiet.

I've just ordered two sensors from ebay (from Latvia) at £25 each. I'll fit them because it's an easy job. If that fails then stuff it.

Let me know how it goes.

I have learned to park by touch, that's what bumpers are for aren't they?

[fjord]

Mr-B said:

Let me know how it goes.

I have learned to park by touch, that's what bumpers are for aren't they?

I'd do the same but i've only had the car for a day lol.

Delivery estimate is not for another week or so, but i'll post here when it's done

[stevesuk]

Hope you managed to sort it out by now?

It is surprising how quickly you get used to having parking sensors. I did without them for the first 15 or 20 years of my motoring "career", but if I was buying a car now, they'd be one of those "must have" features.

Mainly because if I don't reverse my car to within an inch of our garage door, my wife can't fit her car on the drive. Its hard to get that close each time without some help...