Yes - that will happen. It may not be the Nox sensor but can be a number of faults related to the Adblue system. One can be low Adblue in the tank. Perhaps worth checking your adblue tank and put some in if the level is low. Can't remember the minimum but it will be 3+ litres of adblue that it needs (see your handbook for amount and how to do it). 4 posts · Joined 2022. #1 · Feb 4, 2022. Hi, I own a 65 plate cactus. Bought 2nd hand from local garage in 2019. My UREA light has come on (+ service & engine lights) despite topping up my AdBlu. I’ve had the warnings cleared but the fault is continuing to show. I have 600 miles before I can’t start the car. Adblue fault, Citroen c4 hdi 2016, 110000, Knox cencor is…. Any time the Ad-blue fault comes up this indicates that the computer has detected a problem with one of the Ad-blue components. This can be due to a faulty level sensor in the tank, the tank itself, wiring issues, the control unit, a blown fuse, or an exhaust sensor acting up. The subcompact crossover Citroën C4 Cactus is available from 2014 to the present. In this article, you will find fuse box diagrams of Citroen C4 Cactus 2014, 2015, 2016 and 2017 (before a facelift), get information about the location of the fuse panels inside the car, and learn about the assignment of each fuse (fuse layout). See other The Citroen C4 Cactus vehicles affected by this recall were manufactured between 14 May 2018 and 18 June 2019. Citroen recall code: HVX. Affected models: C3 V3 (B618), C4 Cactus, C4 Picasso (B78), C5 Aircross, Berlingo (K9) Vehicle numbers (worldwide): 1,750. Source: Rapex Alert 3/2022 A12/00103/22. In 2019, Citroën announced 25 recalls involving 14 models through the EU Rapex system. The Jumpy and Spacetourer had the most defects, while C4 Cactus the most recalls. We’ve sorted all 2019 recalls according to the model into a table below. Citroën’s most failing cars are still the Jumpy (Dispatch) and Spacetourer vans. The Adblue is carried in a tank fitted near the fuel tank. It is injected into the exhaust system to convert nitrogen oxides. The tank has a capacity of ~17 litres, and will last for 12-14000 miles. It is easy, cheap and safe to top up the system at home. Adding a 1.5L bottle is not enough. You need to add ~5L. The best way of doing it is to add a whole 10L container. (only £10- £12). The warning light should clear without needing to do anything, although it may take a day or two. The capacity of the tank is ~17L, and it lasts 10,000-12,000 miles, so your 1.5L would only last about 1000 miles. To cut a long story short, I drained my adblue tank to a manageable weight (drain plug on right hand side - looking from the back). Removed three nuts and dropped the tank. Disconnected the wiring harness for 30 secs and bashed the cover of the pump with a rubber mallet. Rechecked with Diagbox, cleared the faults. Communications restored. Answer. The urea warning light on our Citroen C4 does not go out because most likely there is a problem with the urea tank. To solve this problem, we will necessarily have to go to a workshop. Posted on: 23 May 2021 by ScegliAuto. eY8e.