PippyT

Thank you guys for all of your responses! I went ahead and got some cheap cats from Amazon and they should arrive soon. I'll definitely make sure to run them hot and get them up to temperature. Hopefully, this will fix it, otherwise, I'll keep you guys posted.

I misread your message, I'm down in Lakewood specifically. Whoops

I'm in Colorado. I guess as of 2021 the state follows the same or similar regulations to California, so there is a required dyno test. There arent any codes sadly, I'm starting to look at the cats. I took it to get retested 2 days ago and it failed again. I never thought about selling my old cats, so I'll definitely look into that. I also found out that the manual version of the third-gen legacy doesn't have an EGR system at all so that would probably explain the super high NOx levels if my cats are bad. I think I'm just gonna go ahead and buy some cheap new cats off amazon and hope for the best. -Thank you

Over the past year, I have been working on my 2000 Subaru Legacy GT Manual in order to get it running smoothly again. It has been sitting since the beginning of January of 2020, and so has the gas. So far I have replaced: Headgaskets Intake Gaskets Exhaust Gaskets Main Oil Seal Oil Separator Plate Cam Seals Water Pump Belts Spark Plugs Catalytic Converter Gasket However, when I took it to get emissions done, my levels of all 3 gases were too high, especially with NOx (see images below). I suspect either the gas sitting in the tank for over a year or forgetting to plug in a vacuum line is the culprit. But considering the car has 175000 miles, there's a chance my catalytic converters could be bad. Right now I've put in fuel system cleaner and 91 octane gas after siphoning out the old gas and running it for multiple hours under load. If you guys have any ideas let me know.