There shouldn't be a separate additive ECU on a C4 Picasso of this year. It should be handled by the engine ECU. That may be why it is nit communicating with it as there isn't one.c4GPicasso wrote: ↑18 Feb 2021, 17:48I managed to top up the additive tank ( very messy ) as the bottle didnt come with a refill kit. I have tried numerous times to reset the counter but the warning still shows up ( im using LEXIA ). Is there a walk through guide? is there a pump to prime first etc? Communication error with the additive ECU pops up on a global test, could this be the issue?
After the Global Test, go onto the Engine ECU, select that and look into the following menus, (Repair / Pack Repair) or may be something else and look for the relevant option around there.
With Mick’s MK I C5 these did have a separate additive ECU and they commonly failed on the early models when trying to reset them, often requiring replacements.
So have another look and let us know how you get on.