]code for catylatic converter check engine light will not go off on 2005 Subaru Forester

do i need to replace the catylatic converter before i register the car I just bought it from a private party used and the light went on the next day after i got it. The other flashing light is the cruise control witch will not engage when you try to set cruise control

Get Your Car Fixed at a RepairPal Certified Shop.
We certify shops based on expertise, quality work, and verified customer reviews
1 answer 3 comments
What is the code for the convertor?
P0420 I bet! Makes no difference, how many replies do we get anyway?
green jelly will fix it. Advance auto has it ....$6.99 per 8oz. jug
Shine is cheaper than that! It will fix anything, for awhile!