I have 2005 545iA and have only one sensor (no M-tech kit and there is only one place for the sensor, so everything is where it should be), and the ACC is working fine.

 

UPDATE!!!

I just went to have a look at the car again if there was no sensor.
I hung under the car and couldn't see anything there,
but when i looked at the bumper again, i saw you could clips off the panel and found this underneath:





Is this the actual sensor?
If so, what do i need to do? (since it seems like it's hidden, maybe too far away?)

I also took a ride to test it again without the panel, and at 50 km/h in the city it actually worked (there came a yellow car and the car slowed down smoothly)

But at 90 km/h it didn't work; i came that close to the car in front i had to hit the brakes since there was a difference of 30 km/h i guess...

 

How bizarre is that?

I have the 535d with ACC also, but no night vision. The sensor on the right in your picture (when facing the car) isn't present on my car and I'm sure that this is for the night vision (which explains why I dont have it). The sensor on the left is dome shaped like yours in the picture but instead of the plastic plate it should have a glass bowl shaped panel in there. Maybe it got cracked and it was replaced with a plain one prior to the car being sold incorrectly???

Ref your issue with the car not slowing from high speed differentials, this is fairly normal to be honest, the ACC can only brake at 4 ms2 I think and if you approach a car/object too quickly it will brake at 4m/s and then beep to warn you that it is approaching the car/object too fast. It's not a collision avoidance system but a comfort feature on motorway driving really. You can increase the driving distance when on clearer roads to help the car identify vehicles earlier and that helps sometimes.

Barry

 

Have you tried the ACC without panel on ?

It could be the sensor you've located, but the wrong panel is in front of it.

 

Thanks for your help already!

Well like i said, i tried it before and it kinda works on slow speeds but not when cruising 90 km/h and more.

 

Sorry, I missed that part in your previous post :-)

To do: visit your dealer - something is really wrong with your ACC.. You still have warranty

 

Thats the first thing we will do when time is right

 

So i just went to my dealer and they say it doesn't work because there is one bolt missing to attach it properly.

The sensor hasn't the stability it needs to respond correctly...

Does this seem to be the correct reason? I don't know, but we can try it...

And a new front panel is ordered