cat_woman88

Help! I just bought a used 2001 Outback several months ago and all of a sudden on a very cold day, my check engine light came on. The auto parts store read it as a P0420 code - catalyst, low efficiency. I don't want to spend a fortune at the dealership getting it fixed if there is something I can do at home. Any suggestions? I have already checked my gas cap and changed the PCV valve.