Citroen C5 X7 ECU communication problems

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Hello
I am have having trouble with my Citroen C5 x7 2.0 HDI 2008.

When i start the car several fault messages pop up, like: ESP/ABS faulty, parking brake faulty, gearbox faulty, depollution system faulty and so on.

I have had luck one or two times with disconnecting the battery then starting with no faults appearing only to come back later.
Tried three different batteries.
Deleted the fault codes in diagbox but keeps coming back. Many fault codes is concerning ECU communication.

Any idea what the problem might be?

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[GiveMeABreak]

Just a few codes then!

One thing you forgot was your VIN code, so we I can relate the codes specifically to your engine ECU.

I suspect that a lot of these are related to the main cause - being that if there is a communications fault in the CAN wiring, or the BSI / Engine ECU is at fault, then this will affect the ability of other ECUs to communicate on the relevant data networks and throw up faults.

One you've provided your VIN, I'll see if I have anything specific.

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Yeah that's quite a bunch!

Yeah right the vin nr.
VF7**************[VIN obfuscated, can be read by forum staff]

Thanks alot Marc, you seem like a very helpful guy!

[chasqui]

Thanks alot Marc, you seem like a very helpful guy!

He most certainly is!!

[GiveMeABreak]

Ok, thanks - I have that, just leave it with me for a bit...

[GiveMeABreak]

Whilst I'm looking at these - can you tell me if there has been any recent work done on the vehicle?

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I have replaced the rod on the hight sensor at rear axle, some time prior to the fault appeared.

And a while back I replaced the heat fan and while doing that the gas pedal was removed. I was just looking at the gas pedal and I can se a blue connector that isn't connected to the anything, is it supposed to??

[GiveMeABreak]

I'm working through these to try and find the common link - and ignoring the faults I know are only associated faults. That is useful. I will check out the wiring for the accelerator pedal.

[GiveMeABreak]

I can't see any reference to a Blue connector - the accelerator pedal has a 6 pin brown connection - so not that. The wiring sleeves should have a code on them (like 1377C0 as an example) - if you can provide any of the codes for the wires on that connector I should be able to tell you what it is for.

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It says 029/08 on the connector but I can't find anything on there sleeve.

[GiveMeABreak]

No, it's the wiring sleeves - some way up that will have the markings - but you may n,ot be able to see it without removing some of the insulation.

Anyway, back to the faults and you obviously have a some communication problems on the CAN networks that connect these systems. My suspicions are the engine fuse box.

These are non-user serviceable, but supply the BSI and the ESP and Engine ECUs and the gearbox locking relay - all these other faults could be symptoms of the main failure of the engine fuse box. There is no guarantee - but given the sheer quantity of these faults this is the one common denominator.

Sometimes the relays embedded in the engine fusebox can fail and this will cause multiple problems.

I would start by checking all the battery wiring, and all the fuses in the engine fusebox first - but again with so many faults it would mean there would have to be more than one fuse shot in the engine fusebox - so I still think this is a likely suspect.

The part number of the fusebox for your X7 is: 9807028580. The cost from Citroen is not as expensive at (UK) £95.71 inc. our 20% VAT - so about 1188.55 Swedish Krona at today's rates.

So looking at the Engine Fusebox, there are direct supplies to the Automatic Gearbox (F7), and multiple supplies to the BSI that in turn is responsible for communication to other systems that are on your fault code list. If it was one or 2 specific faults, then it would likely be a single connection / electrical connector / sensor that would be the culprit. I've also heard the speed sensor being responsible for a load of faults - as this relates to the engine ECU and all systems that are dependent upon this - but again - too many unrelated systems to pin it on an engine speed sensor in my opinion.

I don't think there's much you can do on these test-wise, but if you have checked all your obvious connections, wiring, wiring plugs / battery and supply wiring, then for the price of an hours diagnostic session at a dealer an engine fusebox may be worth a shot.

Consequently, I haven't uploaded over 33 fault code explanations as I don't think under the circumstances it would be helpful given the sheer number of faults and may actually confuse the issue - plus the time involved to do this.

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Well I have spent the afternoon now disassembling and checking the electrical parts, the fuse box, ECU all connections and wiring around them. Took out the fuse box and cleaned it with compressed air and some electric cleaner. The same to all connectors. Checked (again) battery and ground cables (again). Then i started up the car.. but still the same errors came up.

Then i went about to check the gas pedal which was the only error that came back directly after erasing all faults in diagbox. Screwed i off and checked the wiring and connector which i couldn't see anything odd with.
Started up the car and now it seems to working fine!
So far at least. I have tested it for some 30 km with 10 or so startups with no errors.

I guess i was lucky just to try it out, the fuse box seemed like a more viable fault source with so many errors.

Thank you very much, Marc for being so generous with your time and knowledge!

[GiveMeABreak]

No worries - really pleased you have it sorted.

[mihkel]

Hey! I'll hijack this old thread for my similar problems. 2010 C5 X7 2010 HDI 100kW

From time to time (about five times in three years) I've had a no start situation with the car. Turn on the ignition and several faults pop up - gearbox faulty, parking brake faulty, depollution system faulty. After that even the starter does not engage. I know that these fault messages are not plausible as something else is messing with the CAN line or several ECU power feeds simultaneously. The only one that is plausible is the depollution fault as I've got some unresolved faults in the ECU but these can not cause the no start issue. Usually the no start issue is resolved by disconnecting the battery for a fews minutes. The last time it took about half a day and left me stranded.

Yesterday I removed the BSM relay-fuse unit from the engine bay to give it a look and clean. Found out that the module has had water ingress. Cleaned the fuses and fuse holders just for good measure. The car started up fine but I think I'm going to see a new no start failure in the near future.

The faults that can be read with Diagbox (no codes in the BSM)

Engine
P0094 - Fuel system
P0272 - Injector flow correction 4.injector correction time outside tolerance or runaway injector
P1471 - EGR butterfly. Open circuit
P0215 - Injection system supply relay circuit (1 stage)
P1671 - Cruise control. Information incoherent

ESP/ABS
U1308 - Fault: no communication with engine ECU
U1108 - Fault: no communication with engine ECU

Automatic gearbox
U1108 - Fault in communication on the CAN with engine management ECU

Parking brake
U1108 - Absence of communication with the engine ECU

Suspension
U1213 - Fault data invalid of the ECU ABS
U1108 - Fault: no communication with engine ECU
U2006 - Supplier fault code
U2005 - Triggering (vehicle speed receipt anomaly)

[Gogeir]

Hi, i have a the same problem with my CITROEN C5 1.6 HDi 110 Diesel, 9H05 Manual gear.
A lot of erroer codes but the garage found a faulty Engine management computer with part number 657062.
I am looking for a used part, but how flexible can I be with the donor car configuration? I understand the computer needs programing . But can i for example use a part from a automatic when i have a manual?
Appreciate all help.