99 Maxda Protege, 5 speed, one owner, well maintained, 230K miles, and starts easily, runs fine, and consistently gets 30-35 MPG, minor fender bender (radiator, sheet metal, & head light), but the CEL appears intermittently with the P0421 code when I drive it gently. Otherwise. it's fine! The problem has existed for YEARS (mostly a PITA) so I started adding 44k regularly as a preventive about 20K miles ago.
I've seen articles / videos on Seafoam, Marvel, kerosene(?), etc to clean the catalytic converter with a variety of results depending on who you ask. Before I dive into removing / manually cleaning / replacing the CAT, are any of these goo's any good and are there other electronic components which will trigger the CEL / P0421 under these conditions described?
goodoleboy
I've seen articles / videos on Seafoam, Marvel, kerosene(?), etc to clean the catalytic converter with a variety of results depending on who you ask. Before I dive into removing / manually cleaning / replacing the CAT, are any of these goo's any good and are there other electronic components which will trigger the CEL / P0421 under these conditions described?
goodoleboy
