BerserkerX

I drive the IX and have had it for a little over a year now and the service engine soon light is on the code is P0420. Its the catalyst system below threshold i am wondering has anyone had this happen to them before and my mods so far is and AEM short ram intake and Buschurs 3" exhaust with the Buschur muffler any suggestion would help on how to fix the problem

Wheelhaus

iTrader: (2)

You should exercise that search button, I did a quick search and found a bajillion threads.

You most likely need an O2 sensor simulator or something of the like, the rear 02 sensor isn't getting the expected readings because of your exhaust. Do you have an OEM cat, high flow cat, or test pipe?

BerserkerX

sorry thought i had actually mentioned that i did some searching but i am an idiot so ok but i have the highflow cat and thats what i had figured it was before i scanned the car was a catalyst problem and i was looking for some suggestions on what to do thanks a lot. Do you think i should just fix it myself or take it to my mechanic

Wheelhaus

iTrader: (2)

Nah it's not hard.
the Perrin 02 sim is a solder job under the center console, that's what i did with my Invidia 3" TBE. It's an electronic module that simulates what the O2 sensor does if you don't have a catalytic converter. This sim is the cleanest and the little module hides under the center console, but it requires you to splice a few wires and cost about $60.

There's another (cheaper mechanical) fix where you basically use a spacer that bolts underneath the O2 sensor where it threads into the exhaust. Do a search for your code and read some of the threads. You can either use 2 spark plug anti-foulers or a single unit to get the space, can't remember what it's called..

I prefer the electronic fix because once it's installed properly, it's 100% perfect.