Adblue tank repair details

[01484]

Thanks for your reply. I am a bit confused now.
I changed back to the external sensor (Stewart one) 10 bar one and drove for like 2.5 miles. Along the way I had the diagun app open and could see the pressure on the sesnor change from 4 bar to 5.8 and to 6 bar. No errors popped up on dash. It's never moved from 4 bar before so i was happy to see the pressure changing.
I thought the issue was fixed was glad.

Parked up and then I didnt go out the next day so it stood for a day.
Yesterday I drove it again for around 2 to 3 miles and got to destination and parked up, could hear the pump whirring again... I thought ohh no thats it its started again. I just turned car off (didnt get any error) but when I hear the pump after maybe 5 to 6 whirring noises (going on and off) the error pops up on dash saying urea fault.

Im thinking now is that maybe its not the pressure sensor thats actually faulty??

1) I bought the car a year ago and not sure how long the previous owner had it or when they topped the ad blue up? Maybe its very old and starting to crystallise?
Opening the lid of tank its still in liquid form... I did add a bit of ad blue around 6 months ago.
Should I drain it and add that special liquid in which doesnt allow crystals to form and then add new ad blue?


2) maybe air is somehow getting into system from somewhere and then that could be causing pressure to loose somewhere. I did notice when I was disconnecting the pipe...the pipe that comes from front of car and attaches to tank... that connector had white marks (signs of crystallisation) around it? Could this mean a leak and pressure loosing over time causing pipes or sensor to crystallise. I was thinking of cutting it and attaching it directly to the T connector for external pressure sensor but upon looking the connector pipe had 2 blue wires going into it so i cant cut it as it maybe pressure regulated opens and closes.

I have not pierced the member in the ad blue cap shall I remove the membaran and see if that could be a reason for low pressure?


Going to have to do a bit of detective work and see myself... bloody opened it about 10 times so far... feel shattered.
Will report back again.
Thanks for you guys replying will keep you informed.

[Trickiedickie]

Have you previously checked the adblue injector? Sometimes it can have a build up of crystals which can cause these issues. It can be removed and carefully cleaned. And yes it is always a good idea to drain the tank and refill with 10 FRESH litres of adblue and use an additive like Wynns crystal clean and protect. I always check the manufacturing dates on the adblue container and walk away from it if it is more than 3 months.

[Martin Cheney]

I had some similar issues, the last thing I tried was to back flush hot water from the pump into the adblue tank. It came to that after several times of opening the unit up checking various things that I noticed the pick up pipe from the tank to the pump has a really small bore. I surmised that if I had crystals starting to form in the tank that this small bore and the screen within the tank might mean the pump couldn’t get enough suction to build adequate pressure. After flushing though with hot water and refilling with new adblue I’ve not had a problem in almost nine months gone by…if not longer.

[01484]

How did you flush it with hot water?

Been driving it today and it seems to be ok.
Took the diagnostic with me today and could see the pressure sensor increasing to 5 to 6 bar.
So far seems to be ok did around 6 miles today.
Touch wood its ok. Not going to touch or do anything to it. Iv just temporarily put the sensor on above the tank.
Going to drive it at least a week before I mount the sensor properly inside the unit.

[01484]

Right guys!!! I can successfully say that the car has been repaired now. Everything seems to be working. The problem was the new pressure sensor I had bought from alibaba was faulty and the one I bought from amazon (one Stuart mentioned at start of post) works a treat.
Thank you everyone that replied to me. Glad it was fixed otherwise garage would have charged in region of £800-£1000 to fix it.
Glad forums like these exist and people who like to experiment and help others.

[MattBLancs]

Fantastic, so glad it's fixed for you!

I've never dealt with Alibaba (yet) - is the faulty sensor seller going to give you a refund?

[01484]

Yes alibaba have issued a refund for the faulty sensor. Thanks

[CitroJim]

Excellent news

[01484]

I think spoke too soon. Probably jinxed myself.
I think i drove about 40 to 50 miles in total so I was there thinking its fixed as the error usually showed up after 5 miles.
The journeys were short 6 to 7 miles a day.
Yesterday did around 10 to 12 miles constant driving and on way home heard a beep and looked it said engine fault have vehicle repair which shortly followed by the urea emissions fault.
Anyways I got home and put it on diagnostics and the pressure sensor showed 0.50 bar (picture attched).
I cleared the fault code reset everything but pressure still remained at 0.50 bar not sure why. I took tank off again (maybe for 20th time now) disconnected sensor and ran car with faulty alibaba sensor (showing 4 bar) then cleared all codes and reconnected the external sensor (Stewart one) pressure sesnor started working again got to to 5 and 6 bar.
I did read someone was saying their van got 0.50 bar too in previous pages of this forum but wasnt a solution given for it?
Not sure what happened there now?
When i disconnected the pressure sensor i noticed the fluid coming out the the sensor pipe was brown? (Pic attached) but the ad blue in the tank is still clear.
Is the motor causing the fluid to go brown or is it the copper fittings (one on the pressure sensor and another is the copper T connecting the pipes from tank to the sensor)? Could this brown colour of adblue be causing the problem?
Going on a 200 mile journey next month to Birmingham so need this fixing before that. Iv asked a couple of companies and they quoting £150- 200 for adblue delete. Might consider that soon as tried almost everything.

[01484]

Drove 10 miles just now and pressure sensor seems to be working fine kept at around 5.6 pressure. Stopped car for shopping and then drove again pressure sensor kept at 4 bar didnt move, could hear motor whirring n and off whilst driving.
Im starting to thinking this pressure sensor maybe faulty??? Sometimes it works and sometimes it doesnt? I did read a review of someone on amazon saying they recieved a faulty one.
Could try contacting amazon and seeing if they could arrange for a replacement one. Hopefully that works.
If not thats it then paying £150 for it to be deleted.
Will keep you guys updated.

[Trickiedickie]

Or you might consider buying in a brand new tank from Neo Brothers on ebay with a discount code.........£542.25 with coupon code delivered.
Unfortunately might be worth considering even if this is not a repair as discussed.
eBay item number: 285666735004

[01484]

Yes true there's no guarantee 100% if buying a new tank will fix the issue. I did read somewhere maybe another forum that someone had replaced with a new tank then a year and half later the error came up again even with a new tank.
I have read on another forum and thought id share on here too someone has put up a very detailed tutorial up how to fix it. I have not tried it (still thinking of going down the ad blue delete route) I thought id share it on here so it might help someone who is maybe willing to cut tank open and try and attempt a fix.
Link is below. He was saying even if a sensor is not working e.g. temperature sensor or level sensor or heating sensor etc then the ad blue tank will not operate and will not. So it could be a range of different things it could be, by looks of it on this forum mainly people had pressure sensor issues.
What i noticed on mine is that currently its showing 0.50 bar pressure sensor when I start car... and if I unplug and reconnect the same sensor is shows 4 bar and then when engine reaches temperature the system starts working fine... till I stop the car and leave it for a day then when starting it it starts showing 0.50 bar again. It is a small fault somewhere not sure where. Last time when the error popped up after driving 6 miles I stopped and cleared all faults and the pressure still showed 0.50 bar but after few mins of driving it all automatically started working fine... pressure showed around 5.8 bar and remained there for another 6 miles. When it starts working its fine it doesnt stop but only stops working if I park the car and keep it for over night then somewhere something is causing the pressure sensor to read 0.50 bar.


https://www.elektroda.com/rtvforum/topic3827598.html

[altisimo]

Hi!
Have you checked the battery? Ive read about someone who changed the battery and the problem disappeared, apparently there was a communication error with the adblue module due to a low voltage during the engine's start.

[martinwiseman2000]

Hi,

My Citroen C5 BlueHDi has been giving intermittent P20E8 (Pressure of the urea fluid, Urea pressure too low) and P2A00 (NOx sensor, richness measurement faulty) errors. For the last 3 weeks, when doing a longer journey I would get the Urea fault and 700miles until engine starting inhibited dashboard warning, but doing a sequence of several shorter journeys would usually cause these to go away, however now (during very hot weather in the UK) it appears to be permanent. In the context of "shorter" and "longer", I have had the fault reoccur after as little as 3 or 4 miles, but I have also managed journeys of 18 miles without it recurring and once I managed 33 miles before it recurred. After a short journey I have seen P20E8 without P2A00, but on the two occasions I have checked after several hundred miles of driving I see the P2A00 as well.

I have access to Diagbox and a comprehensive range of electrical tools, what I don't have is a lot of time as I'm due to go on holiday in a little over a week's time.

Some questions which I'm hoping someone might be able to answer:
Looking at the wiring diagrams, the urea tank and NOx sensors both look to be connected over a common CAN bus. If there was a fault with this CAN bus, would Diagbox flag it as such, or might these two fault codes be a result of a CAN bus fault?
If the vehicle has started the 700 mile countdown and I subsequently clear the faults with Diagbox, do I always get another 700 miles, or might it just pick up the countdown where it had left off?
I also see the urea temperature reporting as 0°C. I am unclear from the rest of this thread whether this indicates a faulty thermistor which is preventing the pump from running, or whether 0°C is the expected value when the vehicle has not warmed up and the pump is not running?
While I'd prefer to experiment with replacing the pressure sensor, I don't have time to wait for an AliExpress delivery before my holiday. If I need to replace the urea tank, where is the best place to get one. Is this the sort of thing that can only be obtained from a dealer, or are there alternative sources? If I go this route, I'd prefer a proper refurbished one, not a second hand one of unknown reliability.

Thanks,
Martin.