mysterious beeping 2013 Nuevo EK

Can anyone help? Am intermittent beep has just started (every 90 seconds) coming from the rear of the habitation area on this Peugeot Boxer base vehicle. I've checked the smoke. & carbon mono. alarm batteries. Any ideas?
Cheers 
Allan

control panel?
check for low voltage, high waste tank level low water tank level all of which cause "beeps" from my control panel

I would just sit quietly and move a bit nearer in the direction of the beep every time it goes off. 
Might take half an hour but you will pinpoint it eventually.

Fridge door open if fridge is on

Sounds like the control panel giving a warning. I have had this in the past and on one occasion it was due to the fresh water level studs in the tank becoming covered in limescale (it happened whilst we were touring in a hard-water area). More likely however like raymondo says, to be a low water level / tank full level indication. 

Edit: It could also be a low battery voltage alarm.

Hi Folks - many thanks for your replies so far 

Lucy - I've checked the fridge (switched to OFF with door closed = no beeps) 
Spose (& others) - I've filled up the fresh water tank and waste water tank, and , yes, the control panel does beep and flash when both are 100% full (with pump power switch switched ON)....but the separate mystery 90 second-interval beeps is still heard,  Both leisure and vehicle battery conditions are showing good.
It may help you to help me to know that
1) the Peugeot (Boxer) instrument panel was completely replaced when the ABS system was replaced in Nov 2019
2) the previous owner had/has fitted a tow bar
3) the beeps are intermittent (every 90 seconds) and each one lasts for about a second- heard at the back/rear of the van - difficult to be precise as to where!
4) on my last journey an airbag fault showed up on the vehicle instrument panel and then quickly cleared.
5) the beeps still sound with Electric hook Up - both plugged in and out
6) the beeps still sound with the engine On or Off

Any ideas???

In my experience, anything that beeps that infrequently independently of whether the base vehicle and habitation area electrics are on will almost certainly be a low battery alarm. So if you've checked all of the battery-powered things that you know about, the only ones left are the battery-powered things that you don't know about!

My money would be on something like a tracker component or a Mi-Fi adaptor hidden away somewhere that you haven't been told about by a previous owner.

If you reach a blank and still want it found then (and please don't be offended by this) it will probably be pretty easy if you get some help from your grandkids, or any relatives/acquaintances below the age of mid-twenties. It's a well known fact that high-frequency hearing acuity drops away drastically in middle age, so they will ~probably~ have little trouble in locating it (this effect being the basis for the Mosquito devices that have been used in the past to discourage groups of kids around shop fronts).

Grandchildren are in very short supply at the moment as they are all in their homes drawing rainbows.

I wonder if a tranny radio not tuned to a station and on LW or MW would locate it Most of my gadgets generate RF interference.

oldfred wrote:Grandchildren are in very short supply at the moment as they are all in their homes drawing rainbows.

Sorry - I did mean to add the words "when that can be done without any health risk", but forgot to do so before posting!

Another possible aide to locating might be a sound pressure meter - which would permit you to measure the sound level with cupboard doors open and closed, which might - eventually - lead to its location, after extensive testing. I'd probably just leave it until the battery runs down completely instead!

Surely this can’t be that hard to track down??

If the OP can hear it then probably best to leave the grandchildren safely at home. 
I’d never even heard of a sound pressure meter Roopert, nice idea but we are talking about a beep in a small space (please take that in the light hearted way I meant it) 

It may help us to help you if you could say:

What type of control panel / Sargent power unit do you have fitted?

Have you tried turning the control panel completely off (not always straightforward)?

Should there be any kind of plug fitted in the towing socket when the vehicle is not towing?

Thanks Spospe - Control panel - EC328 PSU with a Sargent digital display panel
Cheers Again 
Allan

I don't suppose that your van has something battery-driven which has been introduced, such as a clock? Clutching at straws..... It's got to be something safety-related to make such a sound, fail-safe?

But you remind me of my uncle and aunt (both now dead, in their 90s). When they were in their 80s they walked from their home in Aberystwyth to a public lecture in the University. They arrived a little late; found a seat; and settled down. Until the speaker - alerted by a commotion in the audience - stopped and asked about the loud, piercing, wailing sound. Eventually my aunt twigged: it was a personal alarm in her handbag which my uncle had given her! The audience laughed when, apologising in Welsh, she said that the noise had followed her all the way through the town...

I hope you find the solution, Allan. It must be infuriating. Do let us know.
Cymro

Dbvwt wrote:
I’d never even heard of a sound pressure meter

I think it's a very old-fashioned term - they are more commonly called sound level or decibel meters, and thanks to the Chinese what used to be expensive are now about £10-15 each. But it's a pretty daft idea really, because of the 90s wait that there would have to be between each reading!

But I know from personal experience that it's not always that easy to track down something that makes a barely-audible sound infrequently - it can be a frustrating thing to have to do...

Does the control panel have a button battery back up? maybe ready for change.

Just checked my spare CP, no it doesn't.