"Top up emmissions additive" but Adblue tank is full

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Paul-R
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"Top up emmissions additive" but Adblue tank is full

Post by Paul-R »

First of all an apology for procrastination as the problem first presented itself several months ago and I'm now down to the last 50 miles before starting is prevented!

When the problem first appeared I got a whole raft of different error messages on the display panel. One of them was telling me to top up the Adblue. I thought, well maybe as I filled the tank last summer just before we went to France. That would be 3,000 odd miles plus anything accrued since. However, when I tried topping up it would only take about 3 - 4 litres before it overflowed.

I should have run a Diagbox immediately but I didn't get around to this until a week or two ago. There were quite a few errors logged and I can post them if asked. Most were either irrelevant to the problem and/or were temporary and disappeared after clearing. I'm now left with handful or errors (headlamp, reversing lamp, volumetric sensor, power steering, etc) but nothing in the Engine ECU. And yet the MFD screen error message continues to count down. The countdown message telling me to top up is also the only message now being displayed on the MFD.

These are the two parameter readings for the Denox system in the Engine ECU with engine on tickover.
Scan_20220713-06.jpg
Scan_20220713-07.jpg
I can't see any reason from those readings why I'm getting the MFD countdown. Both screens say that the tank is full (although the second screen gives a value of 10 when the information says the maximum displayed is 6).

Further to this, I was surprised that I couldn't find any way of resetting the countdown using Diagbox. I'm running 7.58 which has been late enough for everything (including coding in a replacement fuel injector) so far. Sure, I have to tell the program exactly what engine ECU is fitted but that's not a problem. I could update to 7.62 if I could be sure that resetting is an option there. Otherwise I'll stay on 7.58. I certainly don't want to go beyond 7.62.

I had to replace the tank back in September 2020 and the car has covered some 10,000 miles since then

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wheeler
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Re: "Top up emmissions additive" but Adblue tank is full

Post by wheeler »

Does your version of diagbox (under pack repair) have the option to reset/reinitialise the denox system? If you have this I would try that first.
The first thing that raises an eyebrow on the live data is your pressure of the urea. It shows the pump stopped. When the pump is stopped the pressure normally sits at 4.000 bar & doesn’t move till the pump starts. The pump wont normally start till the exhaust temp gets to 176 degrees C then it jumps up to around 5-6 bar.
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Re: "Top up emmissions additive" but Adblue tank is full

Post by RichardW »

It's also showing 0 ppm NOX upstream of the cat, but 200 downstream, which looks odd...
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Re: "Top up emmissions additive" but Adblue tank is full

Post by Paul-R »

wheeler wrote: 19 Jul 2022, 12:45 Does your version of diagbox (under pack repair) have the option to reset/reinitialise the denox system? If you have this I would try that first.
It did indeed have such an option. But before I actioned it I did a full error scan and clearing. This is the error listing for the Engine ECU.
Scan_20220719-1.jpg
There are three instances of the same fault, U059E 81. Why three? Anyway they all disappeared after clearing leaving just the Controlled Air Inlet module which I've known about since we got the car and have been meaning to fix.

Anyway, I reinitialised the Denox system after clearing all errors and then took the car for a short run. Everything seems fine now but it'll be after a reasonable run that I'll relax.

wheeler wrote: 19 Jul 2022, 12:45The first thing that raises an eyebrow on the live data is your pressure of the urea. It shows the pump stopped. When the pump is stopped the pressure normally sits at 4.000 bar & doesn’t move till the pump starts. The pump wont normally start till the exhaust temp gets to 176 degrees C then it jumps up to around 5-6 bar.
When I got back from the run I ran the two Denox parameters again.
Scan_20220719-3.jpg
Scan_20220719-4.jpg
The pump is till showing as stopped but doesn't raise a separate error message so is this a phantom fault?

Also, you can see the Upstream NOx content is still recorded as zero. Does this mean that the upstream NOx sensor is faulty? Surely that would have logged an error message though?
As I get older I think a lot about the hereafter - I go into a room and then wonder what I'm here after.

Inside every old person is a young person wondering what the hell happened.

"Trying is the first step towards failure" ~ Homer J Simpson​
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Re: "Top up emmissions additive" but Adblue tank is full

Post by RichardW »

Can you go for a run and record the live data on the Nox sensors? Do they move about?
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Re: "Top up emmissions additive" but Adblue tank is full

Post by Paul-R »

I could if I knew how to do it! Despite playing with these things for many years I'm still very much a novice at most functions.
As I get older I think a lot about the hereafter - I go into a room and then wonder what I'm here after.

Inside every old person is a young person wondering what the hell happened.

"Trying is the first step towards failure" ~ Homer J Simpson​
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Re: "Top up emmissions additive" but Adblue tank is full

Post by GiveMeABreak »

I think you would need to go into the engine ECU and select the option for live data. You can then start the data recording, then go off for a drive and the data will be recorded to the hard drive. If the data is not showing the parameters you want, you should be able to select your own from those shown. May take a bit of trial and error to get what you want.

It can then be played back afterwards.
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Re: "Top up emmissions additive" but Adblue tank is full

Post by Tom309 »

To answer the question on pump status stopped, here is how I believe the system works from my experience last year.
A quick sketch of the main components:
Adblue_block1.JPG
Heating
Start the engine, if the Urea fluid is very cold (frozen), the urea heaters are turned on. There are multiple heaters, one located in the tank, others on the internal components in the tank assembly and on the pipe running to the injector. When this fluid is not frozen /warm enough "injection is authorised" and the heaters are automatically turned-off. I don't know the actual temperature that this happens as I have not investigated at very low temperatures, but I have the impression that this is at 0C. Adblue freezes at -11C so above 0C sounds about right. Note that the temperature sensor is in the bottom of the urea tank.

When the Urea is up to temperature the "Authorisation of the injection of the urea fluid based on the temperature" displays "Injection authorised". After leaving my car for a few hours after a journey, my car showed a urea fluid temp of 8C, injection is authorised and the temperature of the deNox catalytic converter is 27C. So this authorisation is not based on the cat temp.

Pressurisation:
While the cat temperaure heating up, the status was "pump module stopped" + bleed status "on-standby" and pressure 4.0bar*.

When the denox catalytic temperature reached 175C (system 1 info), the pump runs, pressurising the system to about 6.0bar. This is usually after about 5 miles of driving. The denox system bleed status changes quickly (within a second) from standby, to "pressurisation", to "steady pressure - average consumption". The pump status changes to "running" (again within a second) to "pump module stopped with urea solution". The pressure changed from 4.0bar to about 5.9bar (it was not exactly the same end pressure every time, but was between 5.6 and 6.2bar).

From this point the car's ecu can decide when to inject urea into the exhaust based on the Nox in the exhaust. As urea fluid is gradually injected into the exhaust, the pressure slowly drops. The urea is effectively taken from the small expansion tank at the outlet of the pump. When the pressure is a bit below 5bar, the pump is run again for about one second, topping up the fluid back to about 6bar. This is probably after about 20 minutes? This cyle is repeated until the ignition is turned off. After ignition off and a short time (10s?) the pump runs backwards to de-pressure the system. The pressure goes to 4.0bar* and the staus "pump module stopped". Note that it no longer mentions "with urea solution".

*Note that the displayed "urea fluid pressure" does not drop below 4.0bar even if the actually pressure is below this. If the pressure sensor is disconnected then it shows 0.5bar.

So the status "pump module stopped with urea solution" is normal operation. If it is stopped and is not "with urea solution" there is a problem unless it is warming up.

On the Upstream NOx content as zero, I seem to remember the same values with mine. I believe that it was something to do with the NOx sensor being connected directly to the engine ecu/bsi and so not read through the Adblue system. I will try to look this up later.
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Re: "Top up emmissions additive" but Adblue tank is full

Post by Paul-R »

Masterly Tom. I'm glad that my old tank went to such a worthy cause.
As I get older I think a lot about the hereafter - I go into a room and then wonder what I'm here after.

Inside every old person is a young person wondering what the hell happened.

"Trying is the first step towards failure" ~ Homer J Simpson​