2015 1.6 Blue HDi 120 308 Adblue problem

[GiveMeABreak]

^ "I'd never use it" is not an option! ^

You can't drive the vehicle without this system in operation - simple as that. If the vehicle is allowed to run out of Adblue then the engine will not start - it's an EU regulation that inhibits vehicle operation without it and affects ALL modern diesels with SCR systems.

[bill999]

To continue with my testing:
I repaired the old pcb (replaced the Mosfet in the H-bridge that drives the pump motor and put wire links across the two corroded tracks) and also replaced the pressure sensor and the leaky expansion tank by using the complete pump assembly from the 2018 Crossland X tank except for the pcb.
Tried this in the car and it still didn't work even during an extended road test.
Also tried the 2018 pcb, but came back (as expected) with the "No communication to the Denox system" fault.

I was unsure if I still had faults on the pcb, if hadn't properly commissioned (refill, bleeding, resetting) the tank, or if I was not using Diagbox correctly, so as Paul-R was not too far away I asked if I could have the pcb from his old faulty tank. He very kindly let me have the complete tank

Note at the start of the process, I was unsure how the tank could be tested. So I'm not sure exactly when it was working or not, but here is what I did:
1. My tank wouldn't run even when driving the car
2. Inspected Paul's tank's pcb & wiring. Couldn't see anything wrong.
3. Tried Paul's pump assembly (pump and pcb) on my tank, Using Diagbox showed -40C tank temp! I thought it was a bad connection or thermal sensor not connected. Pulled it apart again and found nothing wrong.
4. Tried swapping my tank for Paul's. Still -40C.
5. As my pcb had shown the correct temperature, I tried my pcb with Paul's pump and my tank. Showed +19C.
6. Swapped the two pcbs. Now Paul's showed +20C, but the parameters on Diagbox still showed tank heating, so the car wouldn't allow the pump to run. Note I don't believe that tank heating is required much above -11C (freezing point of adblue).
7. Disconnected and reconnected Paul's pcb. Diagbox box showed that it was no longer in heating mode.
Note I had tried resetting the urea tank faults on Diagbox on the above faults but it hadn't changed temperatures or the heating requirement.
8. Tried the actuator tests again and the "check of the Denox flow" and it started the pump!! Note that the outlet was just connected to a bottle, so would be unable to pressurise.
9. Tried my repaired pcb with the 2018 pump again, it also worked on the check of the flow!

I have found that this test is best for testing the system. I also tried the other actuator tests. The control relay test does nothing, but doesn't fail. The heating tests sometimes pass, sometimes fail, sometimes it doesn't start. I tried combinations of Paul's pcb, tank and wiring and mine all with inconsistent results. I'm totally confused by that as the resistances of my tank, Paul's and the Grandland x are all the same.

10. My last combination was basically Paul's tank & pcb, so I tried a test drive. It worked.
11. The next day it didn't work on a test drive or start the pump on the flow test.
12. The day after that, I pulled it apart, but couldn't find anything wrong or with the parameters on Diagbox and it wouldn't run the pump with the flow test. I was talking to my next door neighbour and was telling him about it, saying that it felt like the problem seems to be one or more poor connections. So I said if I just tapped the pump assembly it would work and guess what, with the screwdriver handle I gently tapped it and it worked!
I put it back together, gave it a test run which worked fine. I was going to do some more testing when it stopped again, but it has now been working for just over a fortnight and over 600 miles.

Note that the original faults on my leaking pump were:
P20F6 Denox leak detection, P249E Depollution of denox - excess amount, P3052 Pressure of urea too low.
These were followed the next day by a host of other faults including P20E8 "low Denox pressure" and U029E "Fault in communication with the denox system - no communication" and the 700 mile countdown. Unfortunately I didn't record them all. I guess this is when the adblue completely submerged the pcb.

My conclusion at the moment is that Paul's tank wouldn't run because of a bad connection. My guess would be the relay contact, but the main wiring connector to the tank wasn't great either, or maybe a soldered joint? I'm waiting for it to fail again to track this down. Note that that cable on the tank had been replaced as it was fitted with one dated 2016. There was a recall for the cabling harness.
I think that the problem of the -40C was the corruption of some parameters when connecting the pcb. I'm still not sure if the heaters will work ok as it's not cold enough to test these properly.
I can't explain why my repaired pcb with the 2018 pump wouldn't originally run on the car (unless it was in the commissioning) as it did work on the actuator test (step 9)

I have stopped testing as the car is still working and I've got to get on with some other jobs, but more to follow.

Thanks again to Paul-R

First of all congrats for your effort!!!
It was really a very interesting thread.
Please tell us, is it still working?
Did you ever located what was the problem with the tank?

[Tom309]

Yes it is still working, so sorry I have not investigated further as I was waiting for and expecting it to be a problem again.
I had one "low Denox pressure" error message shortly after my last post, but it disappeared by itself shortly afterwards and before I could investigate. So I still think a poor connection.
I wanted to also check the heating cycle during cold weather, but the coldest that I drove the car was only -5C. At that temperature I monitored the system, but the heater was not used.

I assume that you have a problem?

[Paul-R]

Hi Tom

Glad to hear that the old tank is still working. I had a problem earlier this year with the new Adblue tank and although none of the errors left after clearing were anything to do with the tank the countdown to inhibited starting still continued. Wheeler was able to give the answer by pointing me at the area in Diagbox to reset/reinitialise the denox system. I did that and haven't had any problem since. So it looks like there was a temporary problem but once in countdown mode the engine ECU couldn't break out by itself.

viewtopic.php?p=723665#p723665

It makes me wonder whether, given your findings on my old tank, doing a reset/reinitialise might have solved my problem at the time. It also makes me wonder whether resetting/reinitialising might be something to try in every case of problems with the Adblue tank.

[Tom309]

I also did some reset/reinitialise on Diagabox during my attempts to get it working. I can't say if it helped in my case, but certainly worth trying as the system seemed to get "stuck" on the wrong temps.

[bill999]

Yes it is still working, so sorry I have not investigated further as I was waiting for and expecting it to be a problem again.
I had one "low Denox pressure" error message shortly after my last post, but it disappeared by itself shortly afterwards and before I could investigate. So I still think a poor connection.
I wanted to also check the heating cycle during cold weather, but the coldest that I drove the car was only -5C. At that temperature I monitored the system, but the heater was not used.

I assume that you have a problem?

Thank you for your answer Tom,
No, i have no problem with my own car. I own a Renault Mégane 2 CC 1.6 petrol. As you probably know my car has many other problems but fortunately no adblue problem.
The PSA ad blue problem is also well known here in Greece where i come from. So when i show the topic i was surprised by your effort.
Congrats to all the members that contributed to this topic. It was really very interesting.

[readie83]

Hi guys, thanks for all of the information on this thread and many others. I'm new to this forum. So unfortunately my 2016 C4 Picasso also has the ad blue problem many others have described. Countdown before starting prevented currently on 600 miles. My local garage initially topped up the fluid (not the ad blue, the other one) - still had the error; then they changed the injector, still the same problem. Now they're saying the pump isn't working and I need a new ad blue tank. According to the garage and confirmed by my local Citroen dealer, the part I need is on back order at a cost of about £937 ex VAT. So, instead I have bought one from ebay coming from France (part number - 9818559480) for about £500 in total. Hopefully it's legitimate and turns up! The local garage said they will fit it, but from reading on here it sounds like I may need to get the main dealer to code the new part in - is that correct? The other thing it sounds like I need to be aware of is whether this is the latest ad blue tank model i.e. there is a risk that I'm replacing one faulty pump with another....although the last one has done 50k miles so I would be OK with that again. Any help or advice appreciated.
Thanks! Nick

[Tom309]

As far as I know (up to about 2020), the only design change to the tank is the interface on the internal pcb. The internals inside the pump/tank appear to be the same apart from this. I haven't heard of them bringing out a newer model (from this/other forums). On Peugeots they changed sometime about 2017, so probably the same for Citreons as it is basically the same internal assembly. I think the change was to try and solve some serial link communiction problems, as they removed a common mode choke. I don't think the change made much difference to the number of failures.
The newer tanks seem to need coding, but I haven't heard conclusively that this is true as someone thought they had a 2015 tank, swapped to 2020 and it worked.
To see what is happening with the tank you need someone who has access to the PSA diagnostic tool Diagbox.

[Paul-R]

I think the coding is something to do with programming of the shutdown sequence which I guess is to prolong the life of the new tank. This is on top of changes to the internals of the tank which are rumoured to have reduced the metal content in favour of plastic.

So, if the coding change is to do with the shutdown sequence then fitting a later tank without coding will work but might not last as long. A further thought occurs to me. Probably too late for most cars but would the new shutdown sequence prolong the life of early tanks?

[GiveMeABreak]

There's no mention of coding the actual tank, but that doesn't mean the tank / pump doesn't need depressurising before replacing it, using the diagnostic equipment which is mentioned.

[readie83]

Thanks guys, my local garage has the diagnostic tool so I'll see how they get on with fitting the new tank when it arrives.

[Ihatethe308]

Hi Everyone

I have an urea light/service light/emissions fault on my 2015 308 allure 1.6 hdiblue. It has been to a local garage to plug in and the message that popped up said UREA pressure too low...

This sounds like the tank issue which I have seen all over the internet the last few days...(since the fault popped up).

Does anyone know of any advice as I can't get into the dealers for several weeks as they are fully booked up and I need this car asap.

Thank you.

Chris

[GiveMeABreak]

Well here's the conundrum:

If it is the pump, then it's a new tank most likely and if you want to try and get some costs fully or partially recovered from Peugeot, then you'll have to let them use a guided diagnostic on it in order for them to make a claim back themselves. There may be a longer warranty on the Adblue tank than the rest of the vehicle.

Having said that, it may also be the adblue injector. If this has been allowed to get blocked up with crystallisation, then this may be causing a pressure issue. It will need investigation to determine what specifically is the problem though, so no magic cures I'm afraid.

[Paul-R]

What are the exact error codes that the garage's code reader found?

[Tom309]

If the faults are only with the Adblue (Urea) system, then it does not damage the car, but the exhaust emissions are too high. So the manufacturer programs the car to allow it to run for a limited mileage before the car must be fixed. The countdown sequence is: Initial Urea/Service fault message followed approx 28 miles later by the message “700 mile until the car can’t be started” (beware that it it countdowns in km so is actually a 700km countdown!). It is also very distracting as the urea light flashes and the message keeps repeating on the navigation screen. After driving for 50km the message reduces by 50km (so 650miles, 600mile,….) Note I haven't tested what happens when it gets to zero!
Some faults with the Adblue system can also be reset temporarily, which will also reset the countdown. So if it is only a fault with the Adblue system the car can still be used for a limited time, or longer if the faults are resettable. Also some tanks have a fault which appears and then disappears.
Did the garage attempt to reset the faults and did they disappear for a short time?

As the fault could be in the Adblue tank, it’s wiring, the pipe running to the injector, or the injector. The fault codes may help to identify where the problem is although data from Diagbox is more useful. A mechanical inspection may also reveal the problem, e.g. look for leaks (white deposits under the car) although the problem is more likely to be the wiring and the components on and inside of the tank.