Abstract: A system to be fitted on an automotive vehicle for injecting reactants in an exhaust line of an engine of the vehicle includes a source of a liquid precursor of ammonia, a source of gaseous ammonia, an injection assembly designed to be fitted on the exhaust line and to inject liquid precursor and/or gaseous ammonia inside the exhaust line, the injection assembly including a single injector body to be fitted on the exhaust line, the injector body having a first inlet for the liquid precursor, a second inlet for the gaseous ammonia, and at least one outlet for injection inside the exhaust line.