Always an ONGOING BEEP - even when car is off

Guy's Please help me here.

I have a Mitsubishi Outlander 2.0 PHEV Instyle+ from late 2013.
The car is making an ONGOING beep that is coming from under the stearing wheel.
Where you have al the fuses and a small valve to open if you need to change a fuse.
The beep does not stop even if you turn the car off and lock.

It's a very high-frequency beep, like these old computer sounds of the 90's.
hard enough to hear it when you are inside the car. Inside the car you need loud music to cover it.
But you cant hear it outside the car.

We have tried everything.
- seatbelts
- every button and switch that the car has
- gear variations
- multimedia system - did not find any setting
- read and reset the software - twice

The technical phone service of Mitsubishi did not know anything about this.

Does anyone have an idea or had a problem like this?
All the help and ideas are appreciated because we can't drive the car like this.

Thank you in advance!

Has it got a Cobra/Drivercard immobilizer? That system has been known to do this.

It does not have an extra security system for as far as Iknow. The normal immobilizer of the mitsubishi key.

It's a very high-frequency beep, like these old computer sounds of the 90's.
hard enough to hear it when you are inside the car.
Inside the car you need loud music to cover it. But you cant hear it outside the car.

You'll have to visit your dealer then. The car has a habit of random inexplicable beeps. Mine emits two series of five from time to time with no discernable reason.

Thank you, let see if someone els did have this problem?

The last time we had one of these it was a failed proximity sensor (after market fitted) or maybe a tyre pressure sensor...

Can't remember which.

Try to record the sound and put it on a file sharing website, and link to here.

That way, other owners may recognise the specific sound.

You can localise the sound with a stethoscope, or a short length of garden hose held against one ear, while probing around with the other end.