Sensor self-calibration system and method

A vehicle comprising:

• an engine;
• a booster having an air inlet for drawing air into the booster and an air outlet for directing air to the engine;
• an exhaust establishing an exhaust passage for guiding products of combustion away from the engine;
• and
• a self-calibrating sensor system including:
• an exhaust gas sensor extending into the exhaust passage for sensing a concentration of a predetermined gas, said exhaust gas sensor including:
• a body provided with a bore;
• a sensing element projecting from the body into the exhaust passage;
• a cap member extending into the exhaust passage and establishing a sensor calibration chamber in which the sensing element projects, said cap member including a plurality of openings for permitting the products of combustion to enter the sensor calibration chamber;
• and a gas inlet tube extending into the bore and being fluidly exposed to the sensor calibration chamber;
• a valve interposed between a supply of fluid containing the predetermined gas at a known concentration and both the gas inlet tube and the sensor;
• a controlling unit for regulating the valve, wherein, during operation of the vehicle, the sensor element of the exhaust gas sensor is exposed to the concentration of the predetermined gas flowing through the exhaust passage and, during a period of sensor self-calibration, the controlling unit shifts the valve to cause the exhaust gas sensor to be exposed to the supply of fluid containing the predetermined gas at the known concentration.