Use of catalysts and sensors

Exhausts gasses can contain pollutants if ideal combustion is not achieved.  Catalysts able to withstand the temperature in the exhaust and ensure that combustion is completed have made a significant contribution to the decrease of pollution from cars.  Changing the fuel air mixture also influences the exhaust gasses.  An engine management system uses a sensor to detect changes in exhaust gas composition and adjusts the supply of fuel to maintain ideal combustion.  The sensor contains a material which changes it’s electrical properties as the composition of the exhaust changes and thus changes the electronic control circuit as the exhaust changes.