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1998 Forester
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I am a Newbie with a 1998 Forester. It has 140K miles and has needed the cam seals replaced for some time. Recently, the check engine light came on and a P0420 code was found. Could the cam seal leak cause the P0420 code? What can I do to fix?

Thanks for any advice.
 

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04 Forester X, MT
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See here:
http://www.subaruforester.org/vbulletin/f88/p0420-catalytic-converter-efficiency-below-threshold-19374/

Basically cam seals shouldn't have anything to do with this code.

Some people have luck getting the code to go away with a "mechanical fix" using the correct thread spark plug anti-fouler plug(s) to remove the rear 02 sensor from the oxygen stream some.

Some people might have to replace 02 sensor(s).

Some people might have to replace cats.

I believe there is also some type of "electrical" fix to trick the ECU.

It all should be in that above sticky thread.
 

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2007 Forester Sports XT 4EAT
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I am a Newbie with a 1998 Forester. It has 140K miles and has needed the cam seals replaced for some time. Recently, the check engine light came on and a P0420 code was found. Could the cam seal leak cause the P0420 code? What can I do to fix?

Thanks for any advice.
I see this is your first post, so welconme to the forum from Oregon! :biggrin:

One of my favorite threads for this is the $5 fix :wink:

When you get the P0420 CEL code, the cause can be:
  • A faulty or failing front O2 sensor (if your gas mileage has dropped off with hesitation, backfires & an overly sooty exhaust tip).
  • An exhaust air leak ahead of the rear O2 sensor (rusted or cracked pipe).
  • A failed CAT.
  • A defective rear O2 sensor.
Bobby...

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