Detection device

An exhaust gas treatment system of the SCR type or for reducing nitrogen oxides and/or particulate emissions of an internal combustion engine

• comprising
• a detection device having a casing housing a circuit arrangement including humidity sensor means, temperature sensor means and pressure sensor means, for measuring a humidity value, a temperature value and a pressure value, respectively,
• the treatment system includes a catalyst device, operatively set along a pipe of the exhaust gas of the engine, and a sensor mounted on said pipe downstream of the catalyst device, for detecting possible presence in the exhaust gas of one of ammonia and nitrogen oxides;
• the detection device is mounted on an air delivery pipe upstream of the engine and downstream of an air filter;
• detections carried out by the detection device at least through said humidity sensor means are used by a control unit for adjusting, together with the detection carried out by said sensor of the treatment system, the amount of a liquid reducing agent that is injected in the exhaust gas upstream of the catalyst device;