Let's hope it is the first possibility. There isn't really an option but to take it to Citroen and have the faults read. I think replacing the Adblue tank is beyond the capabilities of a non-franchised garage, but if it is the sensor you may be able to get it done outside Citroen. See how much AdBlue your Citroen consumes. We base consumption with an average distance of 10,000 per year and a ‘normal’ driving style. Find your model listed below. It includes each variant from years 2015 to 2021. 10 votes, 16 comments. 9.9K subscribers in the Citroen community. News, discussion, pics and video of all things Citroën. And then filled with no more of 5-6l Adblue. I readed this in another forum. In 90% work. I do it this and drived ~600km with message on screen. Now this message go. It's good to see Adblue injector is it clear. There also have a issue. Before to change the tank look first to change the Adblue. The problem is in the Adblue. The Adblue have 18 A big thanks to lancexxx2k off Ebay for providing the diagnostic equipment for this car.Citroen C4 grand picasso diesel additive fault.In this video I detail I have read many times that Adblue replaces EOLYS., so I consulted the head technician and the parts manager at my local Citroen agent, and they both confirm that Adblue fitted cars also have the EOLYS system. The Adblue is carried in a tank fitted near the fuel tank. It is injected into the exhaust system to convert nitrogen oxides. Update. I received my order of Wynn's Crystal Clean and dosed the Adblue tank. After 300kms unfortunately it has made no difference and my level sensor is still causing the Urea light to remain on. Maybe it is broken and not just gummed up. Next step will be to drain the Adblue tank and fill with hot water couple of times to give the tank a clean. AdBlue is a fluid made from urea and water – urea is an organic compound found in the urine and blood of mammals. It’s colourless, odourless and dries to a sticky residue. It’s not toxic but it is a but caustic, so don’t get it anywhere near your mouth, nose or eyes. nBSn.