What do you recommend I do to fix should I do the downpipe and can't delete and then get a tune my car is all stock 2004 wrx wagon i've cleared the code keeps coming back I did an snow x event last sat day and it popped on I've called Subaru dealerships and I gave them the code they told my cat is bad
Found this in the Nebraska Subaru community, -99.9% of the time P0420 and P0430 CEL Error Codes Are Associated Only With The Post (rear) O2 Sensor in modified exhaust systems (in or after the cat). This sensor is also known as the 'Heated Sensor Circuit' or 'Bank 1 sensor 2'. If it is the cat that is bad i would just replace the DP with a new catless DP. I dont think you would need a tune to run a new DP either. If I were you I would get in touch with NF and see what their parts prices are, grimmspeed makes a very nice downpipe.
not sure if the censor info will be relevant to you but if its not the cat going bad that would be your next spot to look
Pretty sure you would need a tune for a catless dp. Get in touch with Nuke at NF. On another note, do you still have that catted up pipe on the car? Better get that off as well. No tune needed for a catless up pipe.
Pick up a downpipe, get ahold of NF (search in the top right of site) and have them install it at the shop and tune it right after. You do need a tune if you run a downpipe. That's what I would do.
Before you go throwing away money, at least inspect the sensor. Its possible that you damaged or disconnected the wiring to the rear O2 sensor at the snow-x. Wouldnt be the first time something like that happened.
I'm taking it into a Scooby dealer on Friday and narrow it down to what it is figured I'd start there it could be the cheaper option
