P0420 CODE
 

Hello all,


Just a little background on my car
2013 Scion FR-S Automatic, 82000 miles, Stock Everything
I just have a quick question for everyone. My car is throwing a P0420 code,
Catalyst System Efficiency Below Threshold (Bank 1).


Now the only reason I'm bringing this on here is if someone could tell me where to start. I have tried that stuff you put in your gas and that made it go away for awhile, but it just came back. I guess the band aid ripped off!!


So all In all I want to march down to Toyota and get them to replace the converter. But I KNOW they are going to run me about 1200 bucks (previous quote). So I don't want to do that and then find out the problem was the 02 sensors or something minute.


So if someone could shed some light or at least point me in the right direction, that would be awesome!


Best Regards,


SHOGUN66

Yes P0420 indicates the ecu "thinks" the cat converter in header is performing below specification.


But it can get fooled by exhaust air leaks ,bad or failing 02 sensors , cracked header


You rearly need to look at logs and evaluate before throwing parts at it


Assume your car is stock with stock header and intake and your running correct fuel


In performance\tuning worlds just pit on a aftermaket catless header and tune would cost less than replacement cat header from Toyota

Also a wiring issue can cause this too.

You can find OEM headers and FP's on Ebay for cheap. People delete cats and sell them all the time. Hell I have them on Craigslist myself. But only the header cat is tested for P0420, don't worry about the FP. Florida has no emissions testing so this is probably the best place to look for them.

Get it diagnosed professionally (yeah it'll cost a few bucks but it'll save you a lot of money in the long run- because if you start throwing parts at the problem not knowing what it is, you'll run our of money before you runs out of guesses!) then you can buy the parts yourself.

If you do need a header, PM me, I have one for sale. It's $150 + shipping not $1200!

Is there some other place other than Toyota that I can get a accurate read on what's wrong, and they wont bullshit me? I guess I will just have to ask around here.


Thanks again man


-SHOGUN66

The only time I've ever had p0420 was when I had a catless header untuned. Your cat may just be done as you suspected. People have blown out aftermarket catted front pipes easily with less miles before. If you had an exhaust leak bad enough to throw a code you'd likely hear it and the code would probably be p0171 or another fuel trim related code due to the fresh air entering your exhaust system.

Call some local shops, ask if they can do diagnosis. Bolting on parts is easy, diagnosis is hard

Hey so if I were going to get the Invidia Headers (SKU: INV-HS12SS1HDP) , would I need to buy any other parts?
Or would I need the front pipe, over pipe, etc?


Thanks

No you dont need to buy any other additional parts. You can just simply swap out your OEM header for the Invidia one. Also, if you do get aftermarket headers you will need to get a tune for it or else you will get other codes as well.

I see a lot of posts about swapping the header. My question is, how does the P0420 code even show up on relatively new cars?

I have a 55k mile FR-S and the code just popped up. It's most surely the O2 sensor because temps dropped around 20F pretty quick from one day to the next in Michigan Oct 2nd week. That probably causes the fuel to run richer. But seriously, should this happen in a barely run (for a Toyota) car? OP is in Arizona so I'd atleast think he shouldn't be seeing this problem?

Guybo - you mentioned it could be a wiring issue - can you elaborate? Would you need a header cat replacement in such a case? Michigan too has no emissions testing, so I can find parts locally with a ton of folks parting out all the time on the MI86 club.

As per posts above, I'm not going to my local Toyota dealer because they want $125 just for diagnozing the problem - I already know what the issue is. Plus parts and labor - the whole thing could run up a bill of $1200 bucks and I'm not trying to get fleeced. But the question remains as to why this should pop in a car so new and driven smoothly without any aftermarket mods. :iono:

I would look further into it before condemning the o2 sensor. Granted, it's not that likely for a cat to go this early either, but stranger things have happened. When an o2 sensor "goes" it'll usually peg in either direction and max out the fuel trims, thus throwing a fuel trim code like max rich or max lean condition, not a cat efficiency code.

Fair point. I was going mostly by my experience as an automotive engineer. Also, under federal law, the catalytic converter and engine-control module are covered for eight years or 80,000 miles. (*Under California law, 15 years). So technically I wouldn't pay anything for a replacement. But my Toyota dealer says this isn't under warranty which leads me to believe they will 'diagnoze', and then only change the O2 sensor/MAF sensor. Big bill.

Also, similar to my thought process is the P0420 OBD II Code help:

Source
This is similar to other information available online.

Anyways, I've given it to my local mech tech and expect to see the estimate/diagnosis of the car back today.