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2000 Forester
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16 Posts
Discussion Starter · #1 ·
I had my 2000 Forester inspected at a state DMV inspection facility and it passed. Then on the way home the CEL light went off. The code is P0420.

Does the fact that this happened literally 2 minutes after an inspection point to the cause?
 

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
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5,732 Posts
^^ Not ignoring the CEL, fixing it. Read the thread he linked to, to show you how to either...

Remedy by spending $$$ and replacing the O2 sensor that the CEL is describing.

--or--

Read that thread and learn about the $5 fix.
 

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2000 Forester
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16 Posts
Discussion Starter · #5 ·
Yes, I read a lot of that thread and my understanding is that there there could be multiple causes for P0420 (cat, 02 sensor, etc.).

I am still wondering if there is anything specific to the very strange timing of when my P0420 code went off that would indicate the exact cause?

I'm hoping that the strange circumstances will help save me some time diagnosing the exact cause.
 

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2007 Forester Sports XT 4EAT
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01 Forester "S" (FS)
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518 Posts
What the other guys said without being glib... like me... Sorry.

Clear the CEL. Replace rear O2 sensor. Install a $5 Fix and drive happy.
 

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2000 Forester
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16 Posts
Discussion Starter · #8 ·
I disconnected the battery to reset the CEL and it came back on as soon as I reconnected the battery and started the engine.
 

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Administrator
2007 Forester Sports XT 4EAT
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Since you know what the CEL code it is, P0420, I'm assuming you had it read. Did you try having it cleared? Not all CEL codes can be reset by disconnecting the battery. :wink:

Bobby...

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

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
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5,732 Posts
^^ This. Have it cleared, then re-start the car and see if it returns.
 

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04 Forester X, MT
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1,039 Posts
they aren't supposed to, but I have had some people let me push the button myself on occasion. you just have to ask.
 

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2000 Forester
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16 Posts
Discussion Starter · #13 ·
Autozone wouldn't clear my CEL.

How else can I clear it? I already tried disconnecting the battery.
 

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Smooshed FOTY 2011
2005 Lifted 2.5 XT 5-Speed MT Dual-Range
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5,732 Posts
^^ Don't go to Autozone, they don't clear codes due to legal reasons. Go to a Checker or O'Rielley autoparts store and ask to use theirs. I've rented their OBDII reader many times and cleared them myself.
 

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2001 Forester S
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32 Posts
O'Reilly's let me use their OBDII Scanner for free. I had the P0420 code come up three months ago. Reset and it hasn't come back since.
 

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2000 Forester
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16 Posts
Discussion Starter · #16 ·
I went to my local Subaru dealer and they cleared the code for free. The CEL stayed off on the way home. So far, so good...
 

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2003 Forester X
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216 Posts
I went to my local Subaru dealer and they cleared the code for free. The CEL stayed off on the way home. So far, so good...
I get the P0420 code at irregular intervals. Sometimes on a 6-8 hour road trip I'll get it 2 or 3 times (I reset it with my Scangauge II), other roadtrips I get nothing. And then occasionally it'll pop up on my 7 mile commute - again I reset it.

I keep meaning to do the $5 fix, but I'm lazy and have better uses for my time considering it takes 10 seconds to reset on the fly. When my mileage goes to crap, I'll fix the problem. Until then...
 
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