2003 Toyota Corolla diagonstic trouble code P0420

If the converter "bed" is broken up, you should hear rattling noise, try rapping on the converter to see if anything is rattling insde it. If so you will need to change the converter, muffler and connecting pipes.50,000 is the recommended 02 sesnsor lifespan, so change it anyway! If the cat melted, you will need to pressure test the exhaust, remove the 02 sensor before the cat, screw in the pressure gauge, take reading, if over 1/12 to 2 psi, replace cat!