Citroen C8 parking sensors module

[manafas]

Hello again
Our recently purchased Citroen C8 has rear parking sensors fitted - but they do not work (never worked whilst the car has been with us).
The day we went to pick the car up we saw a "rear sensors failure" message on the screen as I engaged reverse and then saw the same message a couple more times after that.
Currently it doesn't even show any messages when in reverse, it's like the sensors don't even exist.
So we asked a mobile electrician to come around and diagnose the fault (at a cost), who told us the radio had an error message of not receiving any signal from the parking sensors module.
He went away to find a solution (best option would be a new module as his diagnose was a faulty module) but the next day said the modules have been discontinued and gave us an option to fit new parking sensors system (independent from car and radio, with its own buzzer) for over £300. This is not an option for me, I don't want to spend this much with fixing the parking sensors.
So I located a second hand module unit on eBay for £18 with exactly the same codes/numbers and purchased it.
It arrived this morning and I quickly swapped the cables around from the car's module to the new one and proceeded to engage into reverse, full of hope. Nothing. As if its not even there.
Does anyone know if these modules need to be programmed for the vehicle specifically? I purchased the module as a fully working part, apparently from a Peugeot 207.
Any input will be much appreciated.

The original module

This is the module purchased over eBay

[GiveMeABreak]

Has the radio been changed for a different unit (an aftermarket one at any time)?

If this is the case it can affect the operation of the parking assistance.

Secondly, is it possible that the Head unit (RD4) has been replaced with a second hand unit at some point? If so, the Head Unit ECU may have the programming in from the previous vehicle it came from, - which may not have had parking assistance. There is a specific configuration parameter in the RD4 Radio Head Unit that must be told if parking assistance is present - if this isn't done it won't work.

So in any of these scenarios I have described, you need to get it looked at with a Lexia or Diagbox, so we can see where the faults are likely to be. Then list all and any of the fault codes here.

It is also possible that the system has been deactivated at some point in in the BSI by a previous owner.

So we need some diagnostics to proceed really. It's no good spending money on a new parking assistance ECU if the fault is not in the unit - they are generally extremely reliable and I've not yet seen one case of failure of these. It is the sensors themselves that can fail, but you should get a message to that effect. I do suspect either the head unit has been replaced and not recoded with your car's options, or possibly disabled in the BSI - but wither way you need Lexia to proceed.

[manafas]

Hi Marc
Many thanks for your reply.
I don't actually know if the radio unit has ever been changed, but if it has it's still an RD4.

The guy who come to diagnose the faults had a machine (I don't know what model) whose only faults it found were the radio saying "no signal from parking sensors".
I don't know what code this message was either.

I have sent a txt to the guy asking if he still has those codes on record.

What is Lexia? presumably a diagnose computer?

[GiveMeABreak]

Lexia is the commonly used term for the diagnostic equipment used by Peugeot / Citroen / DS Automobiles for diagnosis of their vehicles and for certain procedures. It consists of the hardware (a VCI) and the Lexia / Peugeot Planet 2000 / Diagbox software used dependent upon the marque. It is used with a laptop.

There is a list of Lexia owners on the Forum willing to help - might be worth looking one up and messaging them:

List of Lexia Owners

At the end there is a link to a Google map with the locations of each, so you can quickly see where they are in location to yourself.

[manafas]

Thank you Marc

[GiveMeABreak]

Just taking a quick look, I know that 'JGRA1' is nearest to you and is also an active member - so try him first 'cachaciero' who is the other nearest hasn't been active since October 2018.

[manafas]

I've sorted it!!!!

Turns out I had the parking sensor option off since I was getting an error - and did not remember I did this until reading a couple of times over your comments.

Your phrase "There is a specific configuration parameter in the RD4 Radio Head Unit that must be told if parking assistance is present - if this isn't done it won't work." made me think what could possibly be the cause of this new module not working at all, not even an error message.

As soon as I turned the function on via the RD4 menu and engage reverse with the new module fitted, it all worked as it should beautifully.
So in the end really was a fault by the module itself!

Thank you for your help!

[GiveMeABreak]

That's ok - they'll be an additional option in the ECU - if this wan't enabled you wouldn't get the option in the Head Unit to disable it - they all work a little differently, but glad you have it sorted.

[manafas]

Thank you Marc