Opinions on "Spacer Fix" for p0420

[phoonTy]

Yesterday while driving home for lunch, our LGT CEL came on. Had the code pulled at Autozone after work and got the print out from them. Code P0420.

I'm going to reset it tonight and see if it comes back.

After reading basically every thread here, on AWDPirates and NASIOC pertaining to P0420, I think I'm going to go the budget route and use the anti-foulers to space the O2 sensor, if the code comes back.

How many here have had P0420 and what did you do to make it go away for good?

I really don't want to fork out the cash for a new 02 sensor, and I'm hoping the CAT isn't gone. The car only has 104,xxx on it. Although, we don't have to pass emissions here.... what will it do to the LGT to just remove the CAT and replace it with a straight pipe?

[sharky nrk]

delete the code from the ecu

nevermind, saw lgt and thought it was ecu flashable - spacer seems to work well in my experience

[Huffer]

How many here have had P0420 and what did you do to make it go away for good?

I really don't want to fork out the cash for a new 02 sensor, and I'm hoping the CAT isn't gone. The car only has 104,xxx on it. Although, we don't have to pass emissions here.... what will it do to the LGT to just remove the CAT and replace it with a straight pipe?

PO420 is Main Cat Inefficiency code. This means there's too much flow happening for the rear O2 to handle. Getting a new O2 sensor may fix the problem.

However, given that you don't have an emissions testing requirement, I would simply drop the cat and have a replacement pipe installed with a bung for the rear O2 sensor, and install it with the anti-fouler method. Probably the cheapest option under $100.

In fact, the muffler place may even be able to provide an O2 bung that is raised enough to avoid having to deal with the anti-foulers.

[phoonTy]

However, given that you don't have an emissions testing requirement, I would simply drop the cat and have a replacement pipe installed with a bung for the rear O2 sensor, and install it with the anti-fouler method. Probably the cheapest option under $100.

I wondered about that option. There's a local exhaust shop that does very high quality work (been in business since my dad was a kid). I may look into that if the code comes back after clearing it.

Thanks for the tip :grin:

[jjs316]

may be a silly question, but anti-foulers are...?

[tnice17]

i have a test pipe and i was getting that code and a malfunction. i replaced it with a universal on from autozone (60$) and used the spark defouler spacer. never saw a CEL since!!!!!!!!!!!!!!!!!!!

[rougeben83]

may be a silly question, but anti-foulers are...?

Small pipe extension, moves your 02 sensor out of the hole in the pipe by about an inch or so...

[jjs316]

Does that just delay its reading or what?

[dplacencia]

I have a high flow cat and haven't had a problem.

[phoonTy]

i have a test pipe and i was getting that code and a malfunction. i replaced it with a universal on from autozone (60$) and used the spark defouler spacer. never saw a CEL since!!!!!!!!!!!!!!!!!!!

I may go that route too. Did you have to drill out the middle of the spacer from Autozone? And do you have a part no. for the universal O2 sensor?

I know it won't hurt anything to drive around with the CEL on, but it bugs me, so I want to make it go away. :lol:

[tnice17]

i dont have the part number but its a 18mm spark plug defouler. i got the short ones so i did have to drill one out. i think if you get the longer ones you dont have to drill it out.

[phoonTy]

okay cool. i didn't make it to the store today, but possibly this week sometime. :lol:

thanks for the help! :cool:

[DLC]

I had a Gruppe-S/Helix installed after putting on my TWE EL headers. The Random cat was tripping 420s with my Borlas on occasion, but the EL headers made it a constant light.

Spacer fixed it:

https://sl-i.net/FORUM/images/imported/2008/02/IMAGE_00134-1.jpg

[hellaGT]

I've got knock off headers, stromung high flow cat (wih rear o2 spacer), stromung midpipe, and stromung axle-back all 2.25''. SOunds great!

I still have 420 codes...Came on about 300 miles after installing everything. will 2 spacers fit/fix the code problem so CEL can go away? I doubt it but I haven't found another remedy other than the 1 spacer.

[Huffer]

Why put in two spacers if one will fix it?

[hellaGT]

I've got knock off headers, stromung high flow cat (wih rear o2 spacer), stromung midpipe, and stromung axle-back all 2.25''. SOunds great!

I still have 420 codes...

The problem is that I have the spacer that "fixes" the CEL but I still have the po420 code CEL on.

[Huffer]

Ah, gotcha. Well, your other option is to test the O2 sensors to see if their voltages are still within spec.
You could try another spacer, if your sensors test out ok.

[anothernord]

With Borla-rep headers and stock cats, I had to use two spacers to stop the code from coming back.

[wrxya33]

may be a silly question, but anti-foulers are...?

Small pipe extension, moves your 02 sensor out of the hole in the pipe by about an inch or so...

Actually they are for spark plugs it keeps them out of the combustion chamber so they dont get fouled. Hence the name. But they work great if you take 2 of them drill one out so the o2 sensor screws in without the tip hitting the anti fouler and screw the other anti fouler onto the first and into your o2 bung. Worked great on my catless wrx a few years ago.

[immortal1kon]

1-check the hose going to your pcv valve, if you are getting alot of blow back oil then your octane levels in the air/fuel mix will be lower causing a CEL.

2-you may also be running too lean

3-fill up with 93 octane next time and see if that doesn't fix the CEL