I have some annoying chirping from behind while driving, but not always. It was hard for me to discover cause so I decided to ask rear passenger to listen and confirm. It happen to be interior alarm sensors housing which have some gap in one side. Since it was not tight vibration during driving caused this chirp.
I was trying to find out how to remove that thing and look what is the problem (probably loosen clip or so) but without success. I suppose there should be clips as usual but, since I'm not sure, I'm afraid to break something so I appreciate help with this.

Edit: I think that I missed correct forum group (I was thinking that I'm in General), so moderators please move it

Just pull it down at the front. will pop off. I had the same annoying squeak on mine. I hit it hard and the squeak has stopped!  Bodsys Brake Bible
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Thank's Bodsy, I am doing the same thing right now as you did