Engine fault light and emissions warning after firmware update- C5 Aircross

[jollyfj]

Hi all,
I had to take my wife for a Hospital appointment today, so while I was waiting in the car park I decided I would make use of the time and run the latest firmware update that came out a couple of weeks ago, and was sat on a usb stick ready and waiting. I think this is the third or fourth update since we got the car new in 2019.
Update ran without a hitch, couple of reboots and done in about 90 minutes, but within a couple of minutes of finishing, the check engine light came on, followed a few seconds later by an emissions warning, then a 'starting will be disabled in 700 miles' warning.
I'm aware of a recall, and apparently this may be related to adblue system issues, and this seems to be a common issue with lots of people advising calling Citroen to open a case with them to get the repair costs covered.
I'm wondering if this is just a coincidence, has this happened to anyone else?
I had already ordered a Lexia cable and got a Diagbox VM running as I'm going to start doing the servicing my self now its out of warranty, but it's not arrived yet and just checking on Citroen's website I can't see a slot in the next two weeks, which is quite annoying as I have a funeral to go to in a few days and I'm going to be travelling at least 800 miles.
Any suggestions at all as to things I might try to clear this?
Cheers!

[GiveMeABreak]

1) When did you last top up your Adblue?
2) If you have been sat with the car idling for 90 minutes in a car park doing firmware updates it may be that the emissions system is recording a fault.

But as it stands, now, it believes the Adblue tank needs topping up, so has flagged up the engine starting prohibiting message. I suggest for now that you call your dealer and tell them the circumstances regarding the funeral and the engine prevention warning - they may be able to reinitialise the DeNox system for you temporarily until it can be looked at.

As for any contributions, you will likely have to pay for a proper diagnostic first so that they can undertake the prerequisite diagnostics required for a warranty claim by Citroen.

They will determine if it is the tank or another part of the system and take it from there. if it's the actual tank, you should be able to get almost the full cost covered I suspect given the age, as long as it has been regularly serviced at the correct mileage intervals or annually whichever comes first.

[jollyfj]

Hi Marc,
I topped it up a few weeks ago. Managed to get the ten litres in and from the sound of the glugs could tell it was very nearly full.
I'm wondering if it's coincidence, but you're told to leave the engine running so the energy saving functions don't kick in, and one update took nearly three hours, so I can't believe 90 minutes would cause an issue, but maybe it's a combination of things?
Anyway, came out this morning for the trip home and it wouldn't start. Turned over but wouldn't fire up at all. Having now read that the issue may result in overfeeding adblue I popped off to Halfords and bought two 5l bags. To my surprise I managed to pour a whole bag in, so I must have used at least 5 litres in about 800 miles, as I've made two trips to London plus some pottering since the top up I mentioned at the top of the post. Kept the second bag as a spare, went inside, had a cup of tea, came out and it started up as normal. Same warnings - engine fault, flashing adblue warning, "You have 700 miles left". Two warnings have now appeared on the 'My Citroen' app too.
Got home after all that without issue, car drove perfectly normally with no issues, now down to 550 miles left, but I tried a warm start after the car had been locked on the drive for twenty minutes and it started fine, so I'm a bit confused about the morning's shenanigans.
Having done some reading we're going to ring Citroen for some 'guided support' on Monday, and see where we go from there, but as you say there will no doubt shortly be a trip to the dealer in our future.
Times pressures for the funeral have eased somewhat as the service has been postponed due to the ill-health of some of the attendees, a bit of a mixed blessing.

[jollyfj]

Just reading up how failed NOX sensor can lead to increased adblue usage so this may be why the tank was so low. We had the same b5.5 130 1.9TDI for twenty years before we bought the aircross, so just catching up on all this adblue stuff.

[GiveMeABreak]

I was just about to say 500 litres in 800 miles is excessive. Your tank has a 17 litre capacity with a range of about 4000 miles on that, so possible you do have a leak somewhere or faulty injector. It should be on average and depending on driving condition about 235 miles per litre of Adblue.

[jollyfj]

Thanks for your helping hand Marc.
My back of an envelope calculation comes out at 340 miles per litre up to today (85 litres in just over 29k), maybe a tad less as the last five litre bag didn't fill the tank. It does mostly motorway miles, ~90%, so I guess that would explain the low usage.
I was thinking of looking at the adblue injector as it's reasonably easy to access, but surely it's unlikely to be blocked if consumption has suddenly risen unless there's a leak, but then a good clean can't hurt, can it?
Of course, it could be jammed open, if that happens. Would a spray with good old brake cleaner help there, or will it be junk?
I've got Diagbox 9.91 running on a VM already, once my cable turns up will I be able to reset the errors if it turns out to be the NOx sensor and I've replaced it?
Cheers.

[Paul-R]

Are there any tests that Diagbox can put the injector through? Listening for clicks, buzzes or whatever?

[jollyfj]

I dunno yet, mine won't do anything without a VCI attached, and that's arriving this week. I expect (hope) there are plenty of diagnostics you can run to test various pumps and injectors.

[GiveMeABreak]

There's always the issue of Adblue Crystallisation. This can block up the injector, first on the inside where the build up continues then it can manifest on the outside of the injector showing signs of white crystals.

Of course there's always the possibility of a leak in the supply pipe. But I do recommend when you get to the bottom of the issue, that you bung in some Wynn's Anti AdBlue with each full top up to help prevent this from happening:

There are some tests I think that can be run - such as pump operation - and the pressure readings - but you have to be careful as this system only operates under certain conditions - so beware of this.

[jollyfj]

Updates...

Yes, a blocked injector is what I was worried might be the issue at first, though I think it may be linked to the downstream NOX sensor as it flagged a fault just after the firmware update, though there have been a few other entries for it prior to this though.
Topped up the adblue and got just two litres in the tank, so consumption was running at around 200 miles/litre over the last 1k, far higher than the prior average.
Reset the deNOX system and cleared all the faults, countdown disappeared and didn't return after a twenty mile test drive on mixed roads, so I've just now returned from an overnight trip to London with no apparent issues.
Will be checking adblue consumption and codes in the morning, if anything looks awry I'll be taking a look at that sensor closely, I guess a misread on downstream NOX could lead to excess adblue injection to compensate.
Cheers...