Subaru 44111AC240 Rear Catalytic Converter

The catalytic converter is an emission control device installed in the exhaust system that reduces pollutants from the exhaust gas stream. It is most efficient at capturing and storing oxygen when it converts the exhaust gases of an intake charge that's mixed at the ideal (stoichiometric) air/fuel ratio of 14.7:1. To replace either catalyst, non-turbocharged models must replace the entire catalyst assembly, while turbocharged models must remove the engine cover, intercooler, engine under cover, turbocharger upper cover, center exhaust pipe, rear oxygen sensor, small bracket on the center exhaust pipe, transaxle, hanger bracket, front catalytic converter from the rear catalytic converter, right exhaust manifold heat shield, front exhaust manifold-to joint pipe, and pre-catalytic converter/joint pipe. Installation is the reverse of removal, using new gaskets at the flange.