C5 Parking Sensor Problem (Bit Strange This...)

[hamster99]

Recently have been getting a fault on my C5 parking sensor system (error message and no display when in reverse) but ignored it as it wasn't critical and have only had time to have a proper look this weekend.

Plugged in the lexia, did a diagnosis and it came up with failed rear sensor. All well and good I thought, so replaced the sensor, checked for faults, all appeared ok. Stuck it in reverse and it works fine but the front sensors dont work. Checked again and did a diagnosis and lexia says the wiring circuits etc are fine, no open circuits, no short circuits (or so it says).

I seem to have hit a wall with this now (excuse the pun!). Is there something i'm missing, like a possible faulty ECU, or something else. Also, is there a way to check the sensors off the car without them being plugged in so I can at least narrow it down.

Cheers

Rob

[vborovic]

If I remember correctly, when the sensors are active, you should be able to feel them if you gently press each one with your finger (there should be a slight vibration felt if the sensor actually works ... you may need a driver in the car plus you outside for this to work out) ... Just in case, did you check for any faulty fuses?

[hamster99]

Checked fuses, all ok. This morning I did get the car display up but it just had a green bar centre front and didn't change at all with nothing in front of it!

[tco_tm]

It is very likely that your Lexia rendered obstacle sensors unit inoperative during procedure of system configuration (page/view with transmission type and front sensors presence).
Check this thread: http://www.frenchcarforum.co.uk/forum/v ... 35#p405435" onclick="window.open(this.href);return false;

[hamster99]

It is very likely that your Lexia rendered obstacle sensors unit inoperative during procedure of system configuration (page/view with transmission type and front sensors presence).
Check this thread: http://www.frenchcarforum.co.uk/forum/v ... 35#p405435" onclick="window.open(this.href);return false;

Thanks for the info. Plugged in Diagbox this week, selected Pug 407, connected to parking ECU to reconfigure front sensors and hey presto, it's all fine again.

Cheers

Rob

[Deano24v]

sorry for dredging up an old thread but i thought it better adding to this than start up a new one.

My 2008 C5 Exclusive parking sensors worked fine and i had the display on the MFD no worries. Got in it this morning and i have no sensors no fault message, no display and no beeps. i tried turning them on and off again via the button, shutdown the car and restarted etc but to no avail. am i missing something obvious?

Thanks in advance

[vborovic]

What sensors do you have on your car, both front & rear or just rear? If you have F+R, do none of them work, or one side works (F or R)? I'd first start checking for the related fuse (on the BSI, or under the steering wheel if you will, find the fuse F14, 15A ... I think that's the one farthest to the right), maybe it is blown ...

[Deano24v]

its just the rear on mine. I pulled the fuse and still no change. Its weird that im not even getting an error tone or error message though and they were fine yesterday

[vborovic]

Did you actually check the fuse, it definitely won't work without it in place ... no, it's not weird, that's how the car functions ... ... if it's not the fuse, you can check the parking computer, which is mounted in the rear left compartment/box in the boot, pull it out, and on the tip you'll see a black box, with 2 square connectors, reconnect and connect both of them ... and try again ... if that doesn't help, you can either start checking the cables one by one from each sensors (electrically), or by using Lexia try to diagnose the parking sensors, and see what you'll get (any malfunctions are bound to be displayed as errors, or will fail the test runs on the parking computer) ...

[Deano24v]

the fuse is definitely fine, but i'll certainly go back and check the module. thanks for your help

[vborovic]

Since there have been a few different cases of parking sensors that just stopped working, please tell us if you figure out what the problem was, so members can reference this in the future ...

[Deano24v]

no worries, will do. The list of things that need looking at just keeps growing

[Deano24v]

for what its worth i took it into Citroen and they were pretty baffled that it worked fine and now doesnt. they advised a new left hand sensor and that would sort it. i replaced it and it didnt! but it does now work intermittently. Ive just turned them off and dont use them. I'll get round to fixing them properly at some point in the new year i guess

[hamster99]

If it's intermittent then I would suspect a loose connector or dodgy cable. All of the rear sensors are part of a single wiring loom which has one connector so would look at that first.
If you have access to a lexia then it will tell you which sensors are not working.

[dnsey]

The transducer connectors are not very well protected from the environment (rear worse than front).
I've had to clean a couple of mine due to mild corrosion leading to intermittent operation.
It's worth going over then all with contact cleaner before doing anything more drastic.