[Mataskart]

I have replaced 3 of the PDC sensors in my e46 with these one's from Hella (2 of the old one's didn't work outright, one showed irregular and wrong readings). There was only 1 good old one I kept, and I checked that it worked fine in all 4 positions so the wiring isn't a problem.
With the broken sensors I used to get a long beep when putting the car into reverse, even with 3 of the new sensors in and the 4th old one unplugged I still got the beep, but when I finally connected all 4 sensors and put the bumper back on, I now get no long beep, but also no sound at all, regardless of how far I am in front of the object behind me.

I checked with INPA and every single sensor was showing up and reading correct distances with a few cm of variance to the object behind, moving back and forward they changed accordingly, didn't get any error codes.

But again, I get no tone to indicate how far the object is behind me, while in ISTA I found a reading that says "PDC System not active" or something along those lines, what could be the cause of this and how would I go about "activating" the PDC system?..

 

[4004]

Well it would be the control unit then.
Check the fuse, otherwise it could be VO coding or the controller itself playing up

 

[Mataskart]

I checked and replaced the fuse, still nothing sadly, as for the control unit there was a whole story around it that you can find in this thread of mine, but basically I already disassembled and checked everything on the control unit down to each contact, and it seemed to be completely fine.
Also the fact that it throws no errors, passes on the status of the 4 parking sensors, and does the long beep if something is wrong tells me it's at minimum functional, if not 100%.

From the hours of googling I did trying to find some more info all I really found was a few russian forum threads with the same issue that they seem to have largely blamed on the Chinese aftermarket sensors they installed. Hella is quite a huge and high end company here in Europe, so they're not really Chinese crap, but they're also not OEM(I think, the salesman did claim they were originals). Also found in some other places that the 2 center sensors don't seem to matter what kind they are, but the 2 outer one's must be OEM otherwise they don't work, but I've no clue from what documentation that came from, and only found a couple mentions of it. My only working original one is installed in the rightmost outer spot, the others are new.

I'm not sure what you mean by VO coding though, could you elaborate?

 

[4004]

VO coding is vehicle order setup (usually via NCS), adding PDC to the vehicle spec - but I very much doubt this is required on E46 for PDC to work (especially since I assume yours was from factory).

I don't think Hella is any better than the chinese stuff in this particular case.
Ah yes, I heard about some issues with outermost sensors not being OEM. I also never found any grounded explanation as to why non OEM sensors can only work in central positions. Given they are all showing correct readings in INPA, I'm not sure that's the issue - but at this point, what else can you try

 

[Mataskart]

VO coding is vehicle order setup (usually via NCS), adding PDC to the vehicle spec - but I very much doubt this is required on E46 for PDC to work (especially since I assume yours was from factory).

I don't think Hella is any better than the chinese stuff in this particular case.
Ah yes, I heard about some issues with outermost sensors not being OEM. I also never found any grounded explanation as to why non OEM sensors can only work in central positions. Given they are all showing correct readings in INPA, I'm not sure that's the issue - but at this point, what else can you try

Yep, it came with PDC from factory, at least it's part of the VIN code, who knows how many of the original parts are still there 21 years later
I think I'll just try my best to buy a used working OEM sensor to replace the outer one(that was the plan from the start- to get 3 used OEM's, but the few scrapyards I went to didn't have any), though that'll be the 4th time I have to take my rear bumper off within 2 weeks, and god-fucking-dammit is it annoying in cold and wet weather, plastic clips just crumbling in my hands freezing from holding the metal tools and bolts.. :')

 

[4004]

Who said old BMW ownership is always fun.
You always defer this till warmer weather, I can't imagine you need the PDC too often on a Compact.
Or you could use inpa in its place

 

[Mataskart]

Who said old BMW ownership is always fun.
You always defer this till warmer weather, I can't imagine you need the PDC too often on a Compact.
Or you could use inpa in its place

Yeah I did wait till warmer weather.... A warmer weekend that is.. Hoped that would be all it'd take me to do this but I was proven wrong once again
Sadly I do desperately need it, my depth perception seems to be horrific, as I cannot tell how far things are behind me whatsoever, if I park just based on looking out the rear window and mirrors, I usually leave a full 3/4 of a car length between me and the car behind... Aka I don't feel safe going any further when I can no longer see the car's behind me bonnet, which is at that ~ 3/4 car length distance, because the rear window in the compact is quite high compared to where I sit at least. So for now I compensate and force myself to drive further than what I feel like is safe by roughly that distance, but this has bitten me a few times over the past year, thankfully not on stranger's cars, but since I have a towhook I have damaged some personal property with it when reversing and would rather not. x_x

Also at this point after nearing 3 months of researching it and trying everything I can to fix it over every weekend, it's now just a sunk cost fallacy (just like the car)- I'm determined to get the PDC system working if that means replacing the entire fckin thing with an aftermarket camera and display )

 

[4004]

Aftermarket might be cheaper in the long run - you will probably get it at some point anyway. Plus I think an aftermarket system can put out PDC readings in a way similar to how iDrive does it (which would be more convenient than plugging in a laptop to park)