DS4 not starting problems

[Mrpink]

Hi,
We have a Citroen DS4 that worked when we bought it, but a week later it wouldn't. - Our first Citroen.

It started with turning the ignition off and removing the ket and the engine kept running so we had to stall it to stop the engine.
Its then had a list of faults on the centre display:

• Engine fault: Repair needed
  Parking brake fault: Have the vehicle repaired
  Tyre under-inflation monitoring fault
  Breaking system fault: Stop the vehicle

This was accompanied by 2 orange and a red parking brake symbols on the fuel cluster, battery, service and STOP on the speedo cluster, and an engine warning light on the tacho.

The parking brake does operate when you pull the leaver, but when you let go it returns without staying on.

The car started up once since then and there was water in the rear row of fuses in the engine bay fuse box. I code read it at this point and had no codes. All fuses were removed and it dried out, then refitted, but the same problems persist. The cable connections in the fusebox all appeared ok and were not corroded

After clearing the faults and re reading (on a Snap-on) I get:
Battery charge status unit (if fitted)
U1F0E
U1F00
B1808
U1802
B1418
B1816
B1809
U1F2E

BSI
U1F0E
U1F00
B1808
U1802
B1418
B1816
B1809
U1F2E

Rain/Sunlight sensor
U1802

Service module
P01B0

Supply protection and management unit (if fitted)
U1F0E
U1F00
B1808
U1802
B1418
B1816
B1809
U1F2E

Monitoring of the blindspot
B1245

When I try to connect to individual computers it brings back no communication with:
Wheel alignment
Engine management
ABS
Electronic parking brake
TPMS
BSI
Electric power steering

Has anyone had anything like this before?
It would seem to me that it is a power supply issue? and that with the engine bay fusebox having some water in I am thinking this would be the cause, however any help is appreciated as its alot of money to throw at it should this not be the cause of the problems.
Does anyone have a fusebox diagram or know which wires to test for power coming out to these modules?


Many thanks

[GiveMeABreak]

If I had to sum it up I'd say you've bought a lemon. Sounds like it has extensive water damage from driving through flooded areas and this has damaged the electronics. A lot of those faults are electronic communication faults between ECUs on the network. If one or more ECUs has been damaged then you have a big job trying track and trace the faults.

If it was bought from a dealer / business / garage - take it back.

I hope you didn't buy it from anywhere near Rufford......

[Mrpink]

Its just one of those things buying from auctions.
Its not been in water and when it ran it sounded great (and these do tend to suffer with the fuse box in the engine bay) which is what is leading me to thinking thats the route cause of the communication issues.
I think if it was as bad as the ones there you'd see its been in water from the headlining alone

[GiveMeABreak]

Actually it doesn't need to be that deep - just idiots driving at full force to try and get through that forces the water up into and over the engine area and in the process gets everywhere and into the electronics.

There shouldn't be water in the engine fusebox - it is well-protected, which is why I suggested it has been in water at some point - and if you've bought it at auction , surely you won't know one way or the other whether it has? Electronic failures can be intermittent, which is why they are hard to troubleshoot - especially when you have so many errors here.

All those ECUs listed are linked via data networks - the BSI is the master ECU and typically the engine ECU is the other main ECU - the rest are all connected and talk to each other. The fact there is no comms with any of them can certainly mean the engine fusebox is not supplying power to the BSI or the engine ECU, so I would start tracing your connections back from the alternator to the battery and to the supplies protection, engine fusebox etc. and take it from there. You need to establish power connections first before looking at the specific ECUs.

[Paul-R]

Did the outside or (especially) engine compartment of the vehicle look as if it had been pressure washed? Pressure washers can force water into the electronics when used carelessly engine bay.