C4 Picasso Mk2 Eolys refill and Diagbox reset – 2014 1.6 HDi

[CallyyllaC]

C4 Picasso Mk2 Eolys refill and Diagbox reset – 2014 1.6 HDi

I know there are already several posts on here about topping up the Eolys additive and resetting the counter with Diagbox, but the useful information seems to be scattered across dozens of pages and several different threads.

I have just done mine this week after the “Particle filter additive level too low” warning appeared at around 103,000 miles, so I thought I would document the whole process in one place.

This was on my 2014 Citroën C4 Picasso Mk2, 1.6 HDi.

Short version:
For my car, Diagbox 7.57 allowed the additive refill procedure to be completed offline.

The refill needs to be registered in both the diesel additive ECU and the engine ECU. Resetting only the additive ECU left the dashboard warning active, despite the additive ECU showing approximately 990 ml afterwards.

Refilling the additive

I bought some 3RG Eolys additive fluid readily available online, after first checking that the particular fluid was suitable for my car.

For diagnostics I also bought one of the clone Lexia 3 / Diagbox USB interfaces from eBay. Mine came from MagikTools, and I can at least confirm that their interface was good enough to complete this job.

I would strongly recommend wearing gloves and putting plenty of cardboard or something disposable underneath the car. Eolys is not something you particularly want all over yourself or the driveway.

First I removed the shield underneath the additive tank.

Apparently half of Lincolnshire had been stored inside mine, because a fairly impressive quantity of mud came down with it. Despite the age of the car, the shield itself came off relatively easily, certainly more easily than the engine undertray normally does.

Once exposed, the additive pipe disconnected without much trouble. It did immediately start dripping fluid onto the cardboard underneath, so having something there beforehand was definitely worthwhile.

I connected the refill bottle and allowed it to gravity feed into the tank.

This takes longer than you might expect. I held the bottle up myself and after several minutes began regretting not recruiting another pair of arms for the job.

Eventually the tank stopped accepting any more fluid. There was still a small amount left in the filling tube which simply would not drain into the tank regardless of how I positioned it.

At that point I accepted defeat, allowed the remainder in the tube to drain onto the cardboard, and quickly reconnected the pipe to the car.

Overall, the physical refill was very straightforward. Excluding a few breaks, it probably took me about 30 minutes, and I was not rushing.

The main warning is simply that it is messy. Expect some additive to drip out during the process and prepare accordingly.

Resetting the additive counter with Diagbox

This was much more interesting. There seems to be quite a lot of conflicting advice online about which Diagbox version to use. I saw recommendations for 7.57, 7.58 and 7.62, so naturally I ended up trying all three, in precisely the wrong order.

The initial menu path is essentially the same.

Diesel additive ECU

Go to:

Repair

Then:

Diesel additive function

Then:

Pack Repair

Then:

Replacement Parts

Then find:

Fill Additive Tank

This is where the Diagbox version becomes important.

Diagbox 7.62

On 7.62, I could reach the procedure but could not actually flag the additive refill because Diagbox attempted to connect to PSA's online servers.

Diagbox 7.58

7.58 behaved similarly. I could navigate through the menus, but the actual refill procedure wanted an online connection.

Diagbox 7.57

7.57 was the version that actually allowed me to complete the reset.

It still displayed a connectivity/service unavailable warning, but after clicking Close around four or five times it eventually stopped complaining and allowed the procedure to continue offline.

After completing this procedure, the additive ECU showed the tank as refilled.

This is the point where I spent far more time than I am willing to admit trying to figure out why the bloody warning was still appearing. The additive counter had definitely reset. I could see it reporting 990 ml, but the dashboard warning remained. It turns out that PSA put effectively the same refill procedure in two different ECUs, because apparently doing this once would have been too straightforward.

Do the same in the engine ECU

I unfortunately did not take screenshots of every menu for this part, but from the main ECU list:

Select the Engine ECU, not the BSI.

Then follow roughly the same route:

Pack Repair → Replacement Parts → Fill Additive Tank

The engine ECU has considerably more options under Replacement Parts, for fairly obvious reasons, so the list is longer than it is in the additive ECU.

Complete the additive refill procedure there as well.

I personally did not erase any fault codes from either ECU during this process, though your experience may vary. I can confidently confirm that I have absolutely no idea what I'm doing beyond documenting what worked on my own car.

Result

After registering the refill in both ECUs, I switched the ignition off and restarted the car.

The “Particle filter additive level too low” warning was gone

Hopefully this saves somebody else from piecing the procedure together from fifteen different posts, trying three versions of Diagbox, and discovering halfway through that their chosen version suddenly wants to telephone France.

[mickthemaverick]

Thanks for posting that, I'm sure it will help many members as time goes by.