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Continuous beep with key turned in ignition

30577 Views 15 Replies 7 Participants Last post by  osama.ismail86
I have a UK spec. late 2003 BMW 325i Sport saloon [E46]. It's a petrol engined car with a manual box. It's been very well looked after from brand new and has led a very easy life.

Having not driven the car for a fortnight, I went to start the car last week. When I placed the key in the ignition and turned to position 1, the mini speaker [or maybe its piezoelectric] beneath the instrument binnacle emitted a constant beeping noise. The audio frequency of the noise is similar to the reverse parking sensor when you're very close to an object, or the blip the temperature alarm emits when it crosses the 3C threshold. The beeping is continuous whether the engine's on or off and whether the car's driving or not.

I've had a good look around various forums, including this one, and other people appear to have had similar problems, but unfortunately those threads haven't returned solutions. Ideas could be :

o A fault ambient temperature sensor, however the temperature gauge reading on the dashboard is accurate.

o Faulty rear parking sensor(s), however I believe that these are trapped by fuse number 24 in the fuse box and having removed that fuse, the sound is still there.

o Faulty parking brake sensor, however I believe that would not usually emit an audio signal when the car is stationery.

There are no warning lights illuminated on the dashboard... so I'm really at a loss to understand what it could be and would be extremely grateful for anyone who has any ideas. Thanks so much.
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I'm not familiar with the rear parking sensors, but have you checked the fuse you pulled out to see if it burnt out? maybe because if it is, it would beep as if it didn't have one:dunno:
sorry cant be more of a help, maybe some of the other festers will chime in

now that I think of it when I put the key in and turn it to position 1, it also does that beep for a couple of seconds
Thanks for getting back to me Ken.

Ya, that fuse looked fine when I removed it. Aside from the nuisance of the noise... it's so loud and piercing, it's really impossible to use the car... I'm worried that it may be some type of BMW 'warning alarm' indicating something more serious wrong with the vehicle... so serious that the car shouldn't be driven.

Hopefully somebody will have come across this before and know what it is and how to rectify it.

Thanks in advance.
from the slight search I did, according to others this is what might be causing it:

faulty parking sensor
hand brake sensor (stops beeping after you pass 30mph)
faulty parktronic control unit :dunno:
low oil level (doubt it)
ignition switch

I'm leaning toward a faulty parking (reverse) sensor
sorry, I couldn't be more helpful I'll try to see if I can find anything else
good luck
let us know how it goes
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Thanks again for this Ken. I'll have a rummage around these things over the weekend. I guess failing that, I need to invest in the software and cables etc... Do you know what's the optimum [best/reasonably priced] set-up to buy for my E46 ? Yes for sure, I'll report back here with whatever I find.
Well I did some fiddling around today [until it started to rain]. Here's what I've discovered so far.

o I checked the oil level and it's mid way between min and max. There's no oil level or oil pressure warning indicators and on start up the engine cycles through the various instrumentation illuminations correctly. The engine runs absolutely fine and as normal.

o I took the car for a drive and exceeded 30mph, the continuous beeeeep didn't stop.

o I disconnected the battery for 10 minutes and touched the two battery cables... this apparently is the technique to cold boot the OBC. It reset the time and tripometer so I guess it did the cold boot.

o All of the parking sensors on the rear bumper [fender] are clicking with a high frequency click when I put my ear close to them and the car's in reverse gear [and the ignition's in position 1 only for safety's sake]. This is the test other people seem to recommend to verify the sensor operation... so I guess I can deduce that they're OK ?

o Fuse 24, the 5A fuse for the parking control system, is absolutely fine. I removed and reseated it to make sure.

o I took a close look at the ambient temperature sensor [located fore of the LHS front wheel arch]. It seems fine and the fact that the instrumentation is giving an accurate temperature reading would seem to indicate it's working fine too.

o The handbrake alarm that emits a beeping sound when the handbrake's engaged and the vehicle's in motion is working fine too... I'll come onto that a little further down.

So, I'm at a loss as to what it could be... based on my trial and error [i.e. non software/fault code] diagnostics. I decided to remove the panel beneath the driver's binnacle, where the offending piezoelectric speaker's located, and I unplugged that speaker. I hate doing things that way as it's obviously a fault of some sort that it's warning me about. I now need to get the diagnostic software and cables etc... in order to figure out what it is. Do you Ken, or anyone else for that matter, know what's the optimum set-up to get for the E46 ? I have two E46s [this saloon and a 325CI Sport] so it will be worth my while.

I tried testing the parking sensors once again with this speaker disconnected and there's no sound from the dash, there's still the clicking sound from each sensor at the rear of the car... indicating that they're working.

Coming back to the handbrake alarm, after having disconnected the piezoelectric speaker beneath the right hand side [driver's side on a UK car] binnacle, I drove the car again and when I pulled the hand brake, I could hear a beep from the dash, so it would appear that sound comes from another speaker ! Probably another piezoelectric one.
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if you want to see if your car might have a pending ses
I'm not too sure if there are auto part stores that can read the codes for free
you can buy a obd II reader (have no idea if that's what your cars have) maybe a peake reader tool

but you might have to go to a experience indie or even a dealership
Thanks for that Ken. I'd like to try and get my head around how the thing works, even if I need to fork out for the diagnostic software and cables, rather than have a service technician take care of it. From a look around the web, there appear to be several different options on diagnostic software... I also noticed some forums specializing in only the software, but as yet I can't seem to figure out which one's best to get. Maybe I need to do some reading/investigating.
Just a thought... Is it raining, or has it rained a lot where you are? My rear parking sensors do strange things when they get wet, as in during a heavy rain or right after washing the car. If I put it in reverse when they're wet, no matter how clear it is behind me, they give a solid beeeep. I would try to investigate them further.

Rear parking sensors are my least favorite feature of our cars.
Thanks for the response Jonathan. No it hasn't really been raining all that much. Bizarre for London at this time of year I know :) It did snow though, but that was after I noticed the problem.

I've read elsewhere that the parking sensors do get upset when they're blasted by water, particularly from pressure washers [e.g. KW] or car washes... so I guess heavy rain would have a similar effect.

As you say, these parking sensors are a fairly temperamental... and from a maintenance perspective at least, something we could do without.

Did you ever find the solution - I am having the exact same issue.

Hi Chris,

Unfortunately I didn't. I had the little beeper speaker disconnected for a few months because it really was undriveable with that noise. I then reconnected it again and there was no beeping sound for a while. It returned and went away again several times. I've since bought all the software and cables and when I ran the car through it, it's clear of faults.

I have been told that it's possibly one or more faulty parking sensors. These are considered 'consumables' by BMW and are expected to be replaced at some point in time. As you can see from the thread, when I tested them, all were fine, so I didn't replace any of them. I believe that the most likely cause is a bad earth. A friend who has had a few E46s told me that they are notorious for earthing problems and the intermittent nature of this issue would seem to point to that.

For now, my best suggestion is to disconnect the speaker. It's under the dash, where your right knee would be and it's a very easy thing to do. It means you won't have rear parking alert working. For the a long term solution, it will involve investigating the earthing problem - quite a time consuming thing I'm afraid :(

Hope this helps, but please let us know how you get on.

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have you looked at the door / boot open alarm circuit
Those would normally illuminate a light on the dash rather than an audio alarm, no ? When I ran the INPA test on the car, they were all clear. In fact everything was clear.
Constant bleep! Soo infuriating

Hi guys i am having this exact same issue although it started after knocking a reverse sensor. But as soon as i turn on the ignition it starts a constant beep. Plugged in the diagnostic expecting it to say parking sensor fault but it says sound generator open circuit short circuit. I assume the blue wire with the grey stripe which goes to the speaker is the culprit as it stops if I unplug it. So I guess it has rubbed through somewhere but I haven't a clue where to start looking. Any ideas?
And here we are! Constant beeping everytime I the car on and only stops when I turn the car off (04 BMW) it started when shady mechanic tried to trick me into “fixing” my cluster which went bad. Ever since he has had it, it won stop. I will say that when it RAINS… the beeping stops and I am at peace but 90% of the time when it doesn’t rain, I hear the beeping even when I am not driving sadly. The shady mechanic said it’s the “blower module” I don’t think he is correct though, does that make any sense? Please any input would be greatly appreciated
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