Join Date: May 2007
Car: 2003 2.5 4EAT with AWP and 2002 3.0 L.L. Bean wagons.
Feedback Score: 0 reviews
I think your mechanic is wrong and whaty he told you is exactly the opposite of reality with our cars (I'm assuming you have an Outback. Year? Miles?)
P0420 is VERY RARELY a failing cat.
It is most commonly a failing oxygen sensor (front Subaru, rear any brand), vacuum leak, exhaust leak or what not.
Search that code on the forums and you'll find plenty of info.
Cats rarely fail without serious mechanical problems, I think your mechanic wants to give you an expensive repair bill.
2003 Outback 2.5 wagon: "Kaylee". 157,000 and counting.
Mods: 2004 Forester XT shift knob, Fumoto oil drain valve, HIR1 high beam upgrade. Also: More rust than I care to think about.
2002 L.L. Bean Limited 3.0 Outback wagon: "Mal". 103,000 and counting.
Mods: Scangauge II, Fumoto oil drain valve, and a decent bit of fixing up to do.