C4 Diesel Adblue Tank

[citroen since 1973]

I agree Marc, thanks. I tow a caravan and a couple of years ago I had a problem with the caravan lights failing, during a nightime return home, on the M40 - not a good time, or place. After fiddling around with the lighting plug/socket and a rest for a cup of tea, this resolved itself, failed again whilst exiting the services and finally stayed on all the way home. I thought it a loose connection in the plug and after checking this and replacing the plug, all seemed good - for a year! The following year, the same thing. The caravan engineer I use recommended changing the connecting lead I use, but this didn't work. I took the socket apart at the rear of the car, but found no issue and the wires all seemed intact, with no loose connections. As I next left home to go on holiday, it failed, yet again, on a Sunday morning. I then thought of asking the AA for help and within 20 minutes a friendly young guy turned up. Very methodically, he worked his way from the back of the car through to under the passenger dashboard, confirming no problems along the way. After 40 minutes, or so, he called me over and showed me a very poor connection, under the dashboard, that had been present on the car from the time it was built! An amazing job by the AA mechanic, that saved our holiday and cost me little, being part of the bank account package we have with the TSB. Maybe I should have called them out to the AdBlue issue!!!!

[morgie]

Has anybody tried Wynns crystal clean & protect adblue additive?

My C4 has thrown up the P20E8 fault: pressure of the Urea Fluid: Urea pressure Too Low.

I put in 10litre back in May when the car was serviced, and after the warning light came up again last week I put in a further 10litres, but the urea light didn't go off so took it to local garage and they showed me the P20E8 fault. They reset it and seemed fine for about 20 miles and the Urea low warning has returned.

I was wondering if it could be crystalizing of urea in the tank and if the Wynn's Crystal Clean will perhaps disonve any crystals that might be causing a problem, before I go down the road of being ripped off by the local dealer.

[RichardW]

I doubt it... most likely the pump and or the ECU is stuffed, and it will need a new tank assembly unfortunately.

[GiveMeABreak]

P20E8 00 does indeed mean there is crystallisation between the UREA injector and the UREA heated pipe. It can occur at low mileage. It is detailed in several Technical Bulletins across the range where this fault code is present.

For P20E8 21 it can also mean other problems, but generally it means the UREA pressure is too low and this can of course be caused by several issues:

Electrical harness
Connectors
Heated urea pipe
Urea pump - gauge module
Urea injector
Urea solution
Urea reservoir

There are checks that can be made before replacing the pump / reservoir assembly though.

As for the Wynn's, I use it regularly. (I dose the purchased Adblue container with a bottle), and then every time I top the car tank up every few months, it is already in the mixture. I prefer to do this every 3 months (but will depend on your own mileage of course), as I prefer not to let the solution get too low in the vehicle tank, so as not to allow too much air to get in and cause rust issues.

The dealers have repair procedures to check for the blockage, so will cost you some diagnostic time, which may not require a new tank.

[GiveMeABreak]

Here are some examples of where crystallisation has happened at the injector and just inside, but of course can happen further back if the heated UREA pipe stops working, or the tank stops heating for example.

[captainpugwish]

P20E8 00 does indeed mean there is crystallisation between the UREA injector and the UREA heated pipe. It can occur at low mileage. It is detailed in several Technical Bulletins across the range where this fault code is present.
...

This is very encouraging. I got the P20E8 00 (specifically 00) code while driving across Europe at the end of the summer when there was a bit of a late heatwave - so nothing to do with crystallisation due to cold weather or heater failure. I'm still hoping that it's just a clogged injector and/or line, and that the bottle of 4TEC anti-crystallisation fluid I bought can work its way through and maybe unblock it. I've read cases where people have done this and have seen the error disappear after a few hundred KMs of driving. My NCT (MOT equivalent) is due in January though, so if I don't see results soon, I suppose I'll need to find a mechanic who'll check the injector to see if it's fouled up.
This AdBlue and the SCR system is a very problematic beast to deal with, and it's a bit of a black box as far as standard diagnostics tools go. The fact that there are several TSBs for this code is good news to me. I don't like the idea of bringing it to a dealer who's probably only interested in selling me the whole tank + fitting for €1500 or whatever they charge, and has no interest in doing any real diagnostics. My car is a 2016 508 RXH with 130k on the clock, so I wouldn't think Peugeot would offer any contribution.

[wheeler]

EDIT: just realised I replied to a post from page 1 by mistake.

[bdonner]

There seem to be a lot of similar or exact copies of issues with the adblue system. I have a 2016 C4 Grand Picasso, which has been warning about Emissions Control Fault, with urea warning blinking and warning about that starting will be prevented in xxx km. Urea injectior changed (there was a lot of crystallized urea on its outside) but this did not end the errors / warnings, and now a urea tank system change for 1900€ is the next that the repair shop wants to do. Many other tell about so similar experiences, where the expensive change of the tank has not helped, so I am very concerned about the situation. We had a very cold period two months ago, with -25 degrees centigrade for many days in a row, this perhaps could have started my problem but as many others have had the exact same problem without extreme temperatures, it is hard to tell.

[TC542]

Hi . . . Another issue with my loverly Grand Picasso .. . ADBLUE pressure . .
I have ordered one . . .But want to reset my counter . . currently at '450 miles' . . (from 750 miles . .) . .to tied me over.
I have a 'FOXWELL' diagnostic tool . . .Any help appreciated . .

[Paul-R]

If your diagnostic tool offers Pack Function, or similar, then look for Reinitialise NOx or Initialise New Urea/Adblue tank then this should do the job. Don't forget to do a general scan and clear of the other DTCs.

[TC542]

Cheers Paul-R . . .I saw 'Pack repair' in the menus . . .I'll fit the replacement tank, try and clear the DTC's . . Then try the 'Pack repair' .
Many thanks . . .

[TC542]

So . . Replaced the Adblue tank with an eBay used one . . At a cost of £260 . . (Had trouble getting the blue cap off . . But a few taps and a bit of persuasion sorted it . . ). Fitted it and added 10 litres of Adblue +WYNNS Crystal fluid. Still had errors and UREA flashing. BUT! . . Resetting error codes . . BSI reset . . nd inally, finding the correct menu to reset 'D-Nox' errors and initialise . . All is now good. . . (The last bit was not mentioned on 'O'Reilly's' YouTube video . . But I'll forgive him . . )
Now to change the 'BPGA' unit . .

[TC542]

I had the '700 mile warning come up . . Replaced it with an eBay/waranted unit . . Fitted it.
Needed to initialise the UREA ECU after clearing error codes. All was working fine for a couple of hundred miles . . Then the warning came up again . . ??!! I decided to change my BPGA unit . . (See my other post on BPGA issues). . and all seems to be good . . Didn't have to reset UREA ECU . . !! Tank is fine.