A catalytic converter reduces harmful exhaust emissions, and it converts gases into water vapour, hence the name catalytic converter. They do have a relatively good life expectancy, but you may find that they are particularly expensive from new. This is because they are coated with powdered catalysts containing metals such as platinum, rhodium and palladium. Occasionally the ECU can play havoc with the Catalytic Converter, making it fail completely, perhaps providing an incorrect amount of air and fuel mixture. In this case always make sure you get your ‘failed Catalytic converter checked out by an experienced professional.