AdBlue Saga

[Simba2016]

Citroen C4 Grand Picasso, Blue HDi 2016.

I bought the car in June 2023 and everything was fine until my first adBlue top up in January 2024. This was my summary of the problem to the local Citroen garage:

=============================
Warning lights: Red "SERVICE" light, Orange "ENGINE" symbol, Orange "UREA" symbol, occasional red banner "UREA Emissions Control fault"
Recent work: AdBlue topped up 3 weeks ago, service
Under what circumstances: Intermittent
Any other info:
On 20 Jan, the orange dash message "Engine fault" appeared, quickly followed by red banner "UREA Emissions Control fault". As we were yards from home we carried onto the driveway. I had a service booked for the 26th anyway and did not use the car until then. The service mechanic could see that the AdBlue had been topped up but no error state was detected. It was suggested that a decent drive could help clear the problem or bring back a readable fault condition.
No error messages were visible until 30 January when a similar set of messages appeared "Red "SERVICE" light, Orange "ENGINE" symbol, Orange "UREA" symbol, occasional red banner "UREA Emissions Control fault" but now with a message that starting would be prevented after 700 miles and the Orange "UREA" light begain to flash. During the journey the count went down to 650 miles. The next day all error indications went off, even the Orange "ENGINE" symbol.

On the 2 Feb the errors indications returned ie "Red "SERVICE" light, Orange "ENGINE" symbol, Orange "UREA" symbol, occasional red banner "UREA Emissions Control fault" and the 700 mile count restarted.
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At this point, I booked the car into local Citroen garage, on the way to the appointment, the errors disappeared again. The garage didn't do a diag as they said it wouldn't show an error and it would still cost.
They suggested a "complete" top up of adBlue and to take it for a "long" drive. Over the next weeks the error occasionally returned and disappeared but the "stop count" did not reappear. The car then had its required service, including emissions and returned with a clean bill of health.

Wind on to June and the MoT, of course the problem returned with more frequency, another full top up seemed to clear the problem and the MoT was passed.

This weekend the errors and the dreaded count down reappeared, I again fully topped up the adBlue and shortly after the count down displayed "start prevented in 3100 miles" for a second and then the whole thing seemed to reset and all is fine again.

[PaulC5]

It could be the complete adblue tank/pump needs replacing but since this is around £1000 I would try Wynn's adblue cleaner which others on here recommend.

[GiveMeABreak]

You really should be using an anti adblue crystallisation additive when you top the tank up. I suspect if you have left it a year that some of the urea has started formulating crystals in the supply line or at the injector itself. I would get some additive in immediately and allow it to work through the system in an attempt to breakdown any blockage. This has worked for others. Then make sure you add some each time you top-up and don't leave it so long before topping up next time. I top mine up about every 3 months or so. I buy the 10-15 litre containers, then add the Wynne's additive to the new container in the appropriate mix and then it's always there ready-mixed in the solution when I top mine up.

Leaving the tank to get too low means there is a lot of air in there and that of course can add to rusting of components and crystallisation.

I use this:

You'll find there are a few brands out there, but make sure you don't get the commercial version of this.

[Simba2016]

Ah, I forgot to say that I did use Wynn's in the early days of the problems (now 6 months of annoyance), I may retry it but its currently not indicating a problem.
I'm especially troubled that this is some weird ECU issue? Surely a real fault would be present at all times and not come and go and no problems have been diagnosed at service and MoT?

[GiveMeABreak]

Not really, as the system operation is constantly monitored, like the flow through along with the NOx levels. Blockages can trigger alarms and also the NOx levels that if not corrected will trigger a fault as it would indicate a possible block / pressure issue or that the NOx sensor is faulty.

That's why I suggested some additive now before the problem gets worse if it is an intermittent fault. Dose the tank up with a bottle and let it do its job. If it doesn't improve then you may well have another issue like a faulty heated supply line, the NOx sensor, injector or the tank pump itself. Unfortunately pinpointing the actual fault does require the codes to be present during a diagnostic, but they should also be able to see any triggered faults from the memory. Having said that, they of course will charge the basic diagnostics charge of about £120 - so at least the dealer is being fair on that point in not wanting to do this until the warning is on.

[RichardW]

You really need to get the codes read; if the light has been on it should have left an intermittent code.

[Simba2016]

Thanks to the last two posters in particular, this forum is great!
I will follow up as suggested.

[TC542]

Hi All . .
Just had the '700 mile' issue crop up . . . Completed the above and reset the error . .
All seems to be ok during a 15 mile trip to get 'WYNNS' AdBlue liquid . . . BUT! the 'SERVICE' light does not reset . . . ??
(Tried the normal service reset . . no good. . . )
Ideas . . .?

[CitroJim]

Hi All . .
Just had the '700 mile' issue crop up . . . Completed the above and reset the error . .
All seems to be ok during a 15 mile trip to get 'WYNNS' AdBlue liquid . . . BUT! the 'SERVICE' light does not reset . . . ??
(Tried the normal service reset . . no good. . . )
Ideas . . .?

It won't. You need to run Diagbox diagnostics on it... That will tell you what the underlying problem is and, if need be, you can reset and get another 700 miles out of it if need be.

Hopefully, your problem will just be the urea injector. These are both easy enough to swap and after-market ones are not terribly expensive.

Don't guess and hope though, get diagnosed and then advise what comes up. Note that a cheap OBD code rear is unlikely to give you the full story...

[TC542]

Hi All . . .again . . .
Toppped up the AdBlue + Wynns . . . Reset the EML/UREA warnings . . .
Car is running perfect;y . . 'No errors' via OBD or car service button. . .Have completed approx 600miles since the 'UREA' warning.
Just the 'SERVICE' light is on . . .
Is there anyone near to Milton Keynes who has a Diagnostic Tool to analyse and reset the 'SERVICE' light . . . ?
Many thanks in advance . . .

[myglaren]

Have a look at this list and the map, read the blurb at the beginning re: contacting members and arranging a session.

[CitroJim]

Is there anyone near to Milton Keynes who has a Diagnostic Tool to analyse and reset the 'SERVICE' light . . . ?
Many thanks in advance . . .

I'm just about to reply to your PM Tony

[Simba2016]

Well, back again!

After taking no remedial actions and 10 months of no issues the AdBlue demons are back - just before MoT time of course!

Car was serviced about 2 months ago and was fine. As MoT was approaching I topped up AdBlue and that seems to have triggered issues again.
The errors were caught at MoT this time:

P208E (temporary fault)
P20E8 (temporary fault)

Fault was cleared and MoT passed with clean emission bill of health.

Next day, the intermittant errors started again.

This is just by way of documenting the issues for the forum.

[Paul-R]

When you say the faults were cleared did you do just that or did you reinitialise the denox system as well?

[merlin667]

P208E is a not properly working ad blue injector nozzle (not opening / jammed).
Is your car smelling like ad blue / urea?
i had it once, reset the error, did not come back for a while. after like one year or something like this i noticed a huge white cloud out of the exhaust. After stopping car smelled significantly like ad blue.
Issue was a damaged injector nozzle. on my 2.0BlueHDI it was like 15mins on two ramps and 130€ for the spare part.

P20E8 is too low ad blue pressure, could be caused by a leak (nozzle) or damaged pump. so which one is first is hard to say