Originally Posted by Nedrex
Either way, it's pretty clear that the car needs a new cat right?
I don't know. No expert here on knowing when a cat is bad, although it is my impression if a cat is bad the engine boggs down and looses power. I'd hate to recommend you spend money if it is not needed. My car threw that code within a week of putting on a band new high flow Invidia catted DP. Others in the 5th gen forum have the same DP as I, but do not throw it. I had to get mine tuned out.
If you are tuning with an accessport. You should be able to download Accessrace Tuner (ART) from Cobb, load your map, then uncheck that code box within ART, resave it, load it on your AP, then reflash your car. Unless you are familiar with tuning, I wouldn't mess with anything else. Another option is to get an e-tune from another tuner on here, have them tune it out (this might be your best bet if you are uncomfortable); or to go get a pro-tune at a place with an all wheel dyno and Subaru friendly. However, that just a way to ignore a potential problem --- if there is one.
It might be worth checking to make sure the sensor is hooked up and functioning properly (how--notsure??). 150k miles is a few.
Proceed at your own risk.