c5 mk1 2.2 hdi code u1000

[ml11ML]

Hi,

recently my c5 got a fault code u1000 (lexia says remote fault, permanent fault, can communications fault bsi communications) on the engine ecu (edc15c2).

As far as I know from other posts this means that the engine should not run at all as the engine ecu can't talk to other ecus (in this case I guess the bsi specifically).

However it works perfectly fine except from a few faults I don't think are related like radiator fan never running (not even with aircon on or a severe coolant overheat) except during a lexia fan test or the misbehaving automatic wiper sensor that randomly increases or lowers the wiping speed as these have been present ever since I bought the car.

There are also sometimes fault codes in the instrument cluster ecu for lack of engine rpm data and similar inputs but I have never noticed the gauges dropping or reading wrong.

The problem is that this fault code triggers the check engine light and antipollution fault message which will cause me to automatically fail the yearly test (MOT) when it's time for that and so I need to find the actual problem and repair it.

Visually the engine ecu plugs and wires look fine but I haven't yet taken it out to check more closely and reconnect them. Any other ideas what to test or check for damage?

Best regards and as always thank you all for any help

[GiveMeABreak]

I'd start by checking tour ABS / ESP ECU - a lot of these communications faults can start from here, interrupting the CAN communication network. Also check under the battery near the looms for broken wires going to the engine ECU.

[ml11ML]

Is the abs/esp ecu located under the main fusebox/engine ecu plastic tray? Either way I traced the wires around as much as I could (without lifting that tray) and nothing looks damaged.

Is it possible that I have somehow messed up the can network by disconnecting the connector to the hydractive ecu/pump unit (BHI?) when I was diagnosing my suspension hardness issues? Surely I would think not because this issue didn't happen for a while after doing that and the car works perfectly fine...

I have also now unplugged and reconnected all the engine ecu plugs as well as the hydractive plug that I messed with before and reset the bsi by following the correct procedure and there is still no change.

Isn't it strange that lexia refuses to clear the code saying "communication problem" but a generic cheap bluetooth obd2 scanner clears the code just fine? Makes me think that this might be a software issue rather than a bad connection somewhere.

[GiveMeABreak]

It's underneath the engine fusebox - so all that assembly and the tray would need to come off.

As far as the diagnostics go, you can't clear a communications fault whilst the fault exists - Lexia is just being realistic.

It is possible that you have disturbed the CAN wiring from the BHI - if that is where you have been recently, then that makes sense to try first. Check the pins are secure as these can become loose if disturbed after a while and the car is getting on now....

[ml11ML]

Thanks for the tip. Will do once the weather improves as it's going to rain all day tomorrow.

[ml11ML]

Okay, some updates...

I removed the plastic engine ecu/fusebox tray to get to the abs pump under it. The plug for abs is somehow smashed in the back (picture attached) so I assume the first owner must have been knocking something around in there as I cant see anything in there smashing it by itself. However none of the wires seem to be damaged and the connector itself seems fine.

I have also checked all other engine ecu and bhi connectors and they all seem fine as do the pins. Car still runs fine besides the check engine light/code.

I have noticed that the can error code only comes up after being wiped when the engine is actually started while another (not connected to this issue, it was always there) code for glow plugs comes up instantly when the key is turned to the on position - even before starting the engine. Is this relevant in any way to diagnosing this or just the way it works?

What is the next step in going about locating and fixing the fault? Remove the BSI (inside the interior fusebox?) and check the connectors on that?

[GiveMeABreak]

Looks a bit of a mess. Although I don't have anything on U1000 for this engine ECU, I can tell you that on the later 2.2 engine with Bosch EDC16CP39 engine ECU, that error means CAN communication: Engine ECU dead.

Looking at the state of that plug, I wouldn't be surprised if there is an intermittent issue. It's going to be something you'll have to investigate a little further - I don't think there's much more we can do at this end to be honest. But I would certainly keep checking the connections to and from the engine ECU.

[ml11ML]

I see, thank you anyway.

Will update if I ever find the issue.

[ml11ML]

Just one more thing... can you tell me what comes up in your database for U1118? While the lexia reads this as U1000 the generic scanner reads it as U1118 (same cause as it popped up at the same time).

[GiveMeABreak]

That code doesn't come up for your vehicle, but this fault is is generally a CAN communication / absence of communication with the BSI.

[ml11ML]

Okay, update...

U1000 is still there however there is now also U1001 but only intermittent not permanent. I have also got an abs fault yesterday after hitting a pothole very hard but that went away after a restart. So that suggests a loose connection somewhere (likely in the smashed abs connector?)

So, what does the new U1001 code mean? Or is it just another generic can fault that gets us nothing new...

Also most ecus in lexia now have the thin red line around the main window which was only on the engine ecu window before (the red line I assume is communication problems? Couldn't find any info about it).

I guess the best thing to do is let the car go even more crazy over some time at which point some useful codes might pop up to point in the correct area with the issue?

[ml11ML]

Final update on this issue in case anyone else finds this...

I have checked all the connectors (including on the bsi which was a terrible experience to get to - even worse than the temperature control motor on the heater flap) and cleaned the contacts and measured the can bus wires which come out fine and cleaned all the ground points. So now I assume the lack of actual faults in the wiring and random errors with most other ecus means that the bsi itself has gone crazy.

Given that the car still works normally and the check engine light stays off after being cleared for a few restart cycles which is more than enough to pass the inspection I have given up on solving this and will just drive the car until something important actually stops working.

[GiveMeABreak]

Unfortunately the nature of 'Temporary Faults' is just that, there one minute and not the next makes fault finding particularly difficult to pinpoint - as in this case as to whether the fault is with the BSI or the communication with the engine ECU to the BSI / vice versa.

[ml11ML]

Hi again,

the constant antipollution fault messages have annoyed me back into trying to get to the bottom of this issue. Could you please tell me the exact path and order that the can bus wires take between the various ecus/modules (engine ecu -> abs -> ? -> ? -> ? -> bsi)? Connector diagrams showing which pins on modules are can bus in and can bus out would be very helpful too if possible. VIN is VF7**************[VIN obfuscated, can be read by forum staff] if needed.

Best regards

[GiveMeABreak]

As per my PM

Injection System Layout Wiring and Location. Note, wires with 900* or 901* etc. are multiplexed VAN or CAN connections (any 4 alphanumeric starting with 9 tend to be these)

Most of the component codes can be found on the wiki:

Wiki Electrical Component Codes


Injection Layout


Injection Wiring


Injection Location


Stability Control

Stability Layout


Stability Wiring


Stability Location