Eolys / PAT fluid replacement - persistent warning message

[Jules]

My other issue reminded me of yet another question I need to ask. This time about PAT / Eolys fluid top up.

I had the message prompting refill of the fluid some time ago. I put 2 litres of PAT fluid into the small tank just forward of the LH rear wheel, via a refill pipe.

I cannot however, get rid of the error code, despite it being cleared by a professional unit (i.e. not a £15 OBDII ebay job) by someone in the trade (although not a Citroen expert).

The AA guy who attended for my other unrelated issue today, also attempted to clear these messages without success.

These are the 2 stubborn messages:
P1446 Additive pump
Below min. threshold value

P15B3 Fuel additive system
Faulty

The second is the code that prompted the initial refill, although I'm pretty sure it never said "faulty" on the other reader, but I could be wrong, or it was hidden etc.

What do you think could now be the issue?

Thanks again!
Julian

[Hell Razor5543]

I think it is likely that (when the code was cleared) the relevant ECU has not had the Eolys level reset. They do not have any measuring device in their reservoirs, so have to be told how much is in there. The ECU 'knows' how much it injects into the system, so will throw up the 'error' when it 'believes' it is running out.

[GiveMeABreak]

A cheap OBD scanner won't cut it. It needs a professional level diagnostic tool to reset the additive counter in the engine ECU.

[Jules]

We did set the level... several different values in fact, with no joy.

@GiveMeABreak - I did say I did not use a cheap ebay diag tool. It was a professional Snap-On tool (unless that was just it's case).

[GiveMeABreak]

Ok, but you don't put any values in. You set the additive counter to zero.

[Jules]

Hi
Finally managed to get my hands on the diagnostics unit again, but setting to zero is definitely not the way. I tried but to no avail.

I don't find any other examples online that set to zero - they all seem to put a quantity in.

Completely stuck now, so will have to resort to dealer...

Thanks for your advice.
J

[GiveMeABreak]

This is the correct way.

It may help if you told us where in the diagnostic menu you went into to attempt this and confirming you are using Diagbox. The requirement is NOT to enter a quantity, but to reset the additive counter. You'll never do it the other way and we only support using Diagbox / Lexia tools as that is what the manufacturer use. We generally can't speak for other manufacturers, so that's something you will have to raise with them if using third party tools.

[Jules]

Hi
It was using a professional SnapOn diag unit.. with a professional at the helm, not me! Although he's not had experience with this car or this issue before.

I believe the menu entered was Diesel Additive... Functional Tests... Special Functions... Fill Additive Tank.

We have tried many values in litres or whatever and zero.

Actual fluid put into tank was getting on for 2l (just less than if I remember correctly).

Again - many many thanks for your input.
J

[GiveMeABreak]

It's likely the diagnostic tool then. It probably does not have the correct software to work with this vehicle. You'll find that after-market diagnostic tools often need updates to maintain compatibility with new engine ECU software released by the manufacturers, (as does their own Diagbox software).

This is especially so with the later C4 Picasso of this year.

[Jules]

OK, well it'll be going to the dealer for a service anyway, so i'll have them take a look now.

He does work in the trade and borrows the unit of an evening, but I guess it's possible that it only gets updated with new info regarding their brand.

It did correctly recognise the engine though.

What I am really scared of is Citroen telling me that it needs a new tank or something hideously expensive.

Will report back...

[GiveMeABreak]

That will be very rare indeed. Eolys tanks are very robust with very few issues reported on these at all (don't get the Eolys tank confused with the Adblue tanks - which are nothing to do with the diesel additive system).

The only time I've been aware of any issues with the Eolys additive tanks are when they have been allowed to run dry through lack of additive - either as a result of unscrupulous people resetting the additive counter without putting any additive in when there is a warning light on or message about this, or because they are too tight to do it and are selling the car on. This leaves the issue for the next owner. Often when this happens the pump runs dry and fails, causing a CAN network communication with the engine ECU. This often results in the need for a new tank as you would expect as they can't be repaired.

As the level of the additive is NOT physically measured, only estimated, the Engine ECU relies on being told that the tank has been topped up (hence the need to reset the additive counter). If this is not done, or it is done and no fluid is added, then of course the Engine ECU will think everything is hunky Dory and keep instructing the additive pump to dose the fuel tank when fuel is added - until the pump runs dry and fails.

[RichardW]

I can't think in the few I have done I have ever entered a value, you just go via special functions and refill the tank, and it just asks if you've refilled the tank. You may have to do it twice - once in the additive ECU and once in the Engine ECU, and then clear the codes to get the light off. Not done anything as late as 2017 mind you....

[Jules]

Thanks.

Booked in - they say it may just need re-priming (as well as the standard diag resetting). Wish me luck.

Interesting re doing it twice Richard. I'm pretty sure we did set it then clear the codes. Went round in circles in the end so I think we had most options covered with multiple attempts!

J

[GiveMeABreak]

Re-priming is required on some engines - which I forgot to mention, but in Diagbox the option is there in the same place along with the additive refill.

[wheeler]

I just use the refill tank option like richard.
You use Zero when replacing the actual DPF, you set the amount of fluid deposited into the filter to zero as its a new filter.