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2001 Forester
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Discussion Starter #1
Hi, I have been searching in vain for an explanation of the $5 fix (mechanical) for the PO420 code that I have seen references to. Would someone be kind enough to point me in the right direction to it please?
Thanks
 

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2007 Forester Sports XT 4EAT
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Installing the $5 fix on an '05+...

@bbco a forum search for spark plug non-fouler will get you to this thread: new Cats and O2 sensors

Update ► Starting in '05, the rear O2 sensor is used for fuel trim, so the $5 fix should be used with caution on the '05+! You could get a P2096 CEL code - Post Catalyst Fuel Trim System Too Lean Bank 1.
On the positive side, some '05+ members have had good luck using the spark plug non-fouler... spacers. It doesn't hurt to try it, as it can be removed if other issues popup.

Bobby...

['07 FSXT Member Journal] ['03 X Member Journal]
 

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Discussion Starter #4
Thanks for the info. Do these sparkplug non-foulers come in various sizes/threads? If so, which size would I need?
 

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Thanks for the info. Do these sparkplug non-foulers come in various sizes/threads? If so, which size would I need?
Yes they come in different sizes. You want the 18mm, either the one with the gasket (crush washer) or the taper seat. If I had to do it over, I'd go with the tapered seat, since the crush washer is a PIA to seat (crush) correctly!

I attached what they look like in a package. The one pictured is the one that comes with crush washers. You should be able to find these at any auto parts store. If you read the info I linked you to, you know you'll have to drill one out with a 1/2" (13mm) drill bit. You only need to drill out one spacer, the one that the O2 sensor screws into. Don't forget to use anti-seize on the threads!

Bobby...
$5 spark plug non-fouler.jpg Napa_7302442.jpg
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Discussion Starter #6
Thanks once again. Since I reset my CEL a few days ago, all has been well so I'll look for the anti-foulers so that I am ready for the next occurence. I live in Alberta Canada so I expect they'll be available somewhere around.

Anyone know of Canadian companies that carry the anti-foulers? I looked all over town for them on Saturday.
 

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They can be found in most any auto parts store (NAPA, AutoZone, etc) where I live. You need to make sure you ask for a "Spark Plug Non-Fouler" & don't mention anything about CEL issues or using it to space out your O2 sensor. If you do, it will confuse the parts guy & they won't be able to find the part!

Bobby...

['07 FSXT Member Journal] ['03 X Member Journal]
 

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Discussion Starter #8
I'll look again. Do we have to buy O2 sensors from Subaru or are they a standard item like spark plugs etc?
 

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You can shop for them on the internet if you're not in a hurry. The front 02 sensor (A/F or Air/Fuel) is critical for correct engine operation, so that one I'd pay to get an OEM/factory part. The rear O2 sensor is just used to monitor the CAT, so you can shop around for deal if you need to replace it.

Bobby...

['07 FSXT Member Journal] ['03 X Member Journal]
 

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Discussion Starter #10
I notice a few rear O2 sensors on Ebay, various manufacturers. Anyone have any recommendations. It would be nice to have one with the correct connections on it I suppose. Soon I'll be on my back in the snow here :(
 

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I notice a few rear O2 sensors on Ebay, various manufacturers. Anyone have any recommendations. It would be nice to have one with the correct connections on it I suppose. Soon I'll be on my back in the snow here :(
To tell you the truth, I bought both front & rear O2 sensors from my local Subaru dealership. Yes, it was more expensive, but I know it's made for our '03 X, plus it will fit & work correctly.

Bobby...

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Discussion Starter #12
For any other Albertans on here, I found the anti-foulers at NAPA. They didn't have 18mm ones in stock but have ordered them for me. Should have them tomorrow.
Bobby, I will probably also get mine from Subaru, at least the first time. :)
 

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Are there any differences for the $5 fix for a '99? Most of what I have seen mentioned is for '02 on.
 

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It should work as long as the spacer(s) fit. have you looked here?

Bobby...

['07 FSXT Member Journal] ['03 X Member Journal]
 

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Newbie and the $5 fix

Hi all
Google brought me here, and I am hoping the $5 fix will work for my PO420 code woes.

My mechanic says he beleives my O2 sensors are good and that if I can find a decent aftermarket (or OEM) cat, he can install it pretty cheap.

However, I have 150K on my Forester, so I thought the $5 fix would be an interesting experiment anyways. My car seems to be running great and mileage has never fluctuated greatly (although I don't track it very accurately).

In case the anti-fouling spacers don't work, I wonder if anyone has specific brand suggestions on a replacement Cat for the 2001 Forester. I see internet prices from $250 to $500. Also, cna you confirm that the aftermarket models are single units instead of two "pods"? My mechanic was explaining the new style to me, but I can't recall if he was talking about the OEM replacement or not. I don't want to buy garbage and set up an installation nightmare or heat shield issue - I've seen what overheating can do when it melts out a CV boot and coats the exhaust with grease - ugh.

Anybody bought one and had it installed without much ordeal by a local mechanic (i.e. not a dealer), and had good results/longevity from it?
Tnx
 

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I see this is your first post, so welcome to the forum! :biggrin:

If, as you say, your '01 is running normally. The $5 fix couldn't hurt. You should be able to have any trusted muffler shop install a universal CAT for around $200.

Keep in mind, if you live in the DEQ testing area, the $5 fix won't help with emission testing, so eventually you may have to fix the actual fault.

Bobby...

['07 FSXT Member Journal] ['03 X Member Journal]
 

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Tnx Sleeper

A couple of more items. Another poster suggested driving at high rpms for a bit to "blow out" the accumulated buildup in the Cat. I always thought this concept was a bit of urban myth, and likely to cause more harm than benefit. Anybody know if this might actually help - I usually drive like a Granddad and I think my cars last quite a while because of this.

Also, I don't have a great deal of experience with "trusted" muffler shops. I don't frequent them, and I guess most of the feedback I hear is the negative stuff when things go wrong. If I replace the Cat, I had planned on getting my mechanic to do it. Do you think an exhaust shop would be more savvy in getting things to fit right since they would presumably do more of these?

Oh yes, my car is a 2001 Forester L automatic. Very basic. I do almost all highway miles on an Interstate at about 60-65 mph (Granddad, I know) with one passenger. I pull a very light sport trailer most of the time - about 250 lbs with 30 lbs tongue weight.

Cheers
 

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If you install the $5 fix because you have other issues, no. The purpose of the spacer is to move the O2 sensor back out of the exhaust flow. If they use a tailpipe probe to check your emissions, you may fail.

Bobby...

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