Parking sensor replacement question

[Jagdpanzer38t]

Hi guys. Today my father managed to damage my rear bumper while reversing and I thought it's about time I did something about the not working parking sensors...

Using the ticking/beeping trick I diagnosed that 3 out of 8 sensors are not working. I found a little trick about WD-40 an sprayed them all from the outside. After that one of them started ticking again.

Right now one in front and one in rear are not working. I have the E53 from 2006.

https://www.realoem.com/bmw/enUS/sho...diagId=66_0009

Front center right (being held by part number 10) and rear side left (held by part nr. 8). Are there any tricks to replacing them or some guides out there? I think it's possible to replace the rear one without the need to remove the bumper. What about the front one, does the bumper need to be removed (looks like a pain in the bum). My X5 also has underride bar like in the pic (not my car, mine is the facelift version from 2006):



So if the front bumper needs removal (pls no) does the underride bar also need removing (oh God no)?

While we are on the subject can you recommend whitch sensors I need to buy. I heard the stealership can charge ~100-150 Eur for a single sensor whitch is crazy. I was checking aliexpress and some of the sensor connections are bent into one direction and others into another ugh... Would like to get one that works...

https://www.aliexpress.com/wholesale...parking+sensor

Also any way to check if it's a faulty sensor or wiring gone bad?

And last bit my sensor holder (part nr. 8) is damaged, do you know how much one is worth? Oddly enough the damaged side with hanging sensor is working...

Sorry for the long text lol