This function is used after topping up reduction agent (AdBlue) to reset the indicated reduction agent reservoir's level to full. Cars equipped with an SCR-system (Selective Catalytic Reduction) use a urea ammonia nitrate-based reduction agent, also called AdBlue, which is injected in the exhaust system in small doses to reduce exhaust emissions. In cars equipped with an SCR-system, reduction agent must be used according to legislation, in case of system malfunction or shortage of reduction agent the car cannot be started. The reduction agent is stored in a separate reservoir, it is not mixed with the diesel fuel.