DTC PO440 won't clear/self test - Subaru Forester Owners Forum
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post #1 of 5 (permalink) Old 07-25-2012, 03:12 PM Thread Starter
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Join Date: Jul 2012
Location: Sherwood, OR
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Car Year: 98
Car Model: Imp RS
Transmission: 5 MT
DTC PO440 won't clear/self test

New to forester.org, but have been on USMB for awhile... Trying this issue out here to see what ya'll think.

1998 Forester 5MT
150,xxx + miles

Charcoal canister replaced
Shut valve replaced (little valve near top of filler neck)
Filler neck replaced (rusted enough to cause a problem soon)

If drain is plugged (removed from frame rail and rubber plug inserted.) system will build pressure to over 1.0" Hg.

My understanding is that the fuel tank pressure should cycle between .250" - .500" Hg when left to idle for a half an hour or so.

Watching the numbers, the pressure cycles, everything looks normal.

The memory has been cleared, 7 of the 8 OBD tests have self checked, Evap emissions still not "ready".

What steps need to be taken to get the computer to check itself off and now pass emissions? (Vehicle was originally tested with PO440 code, thus, evap must be "ready" with no evap codes)

Lewis
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post #2 of 5 (permalink) Old 07-26-2012, 01:28 PM
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Car Year: 2007
Car Model: Forester XT
Transmission: Auto
Plug green diagnostic connector together and go for a test drive (55mph+, steady throttle (not steady speed), and see if that helps. That should force the test.

Also, you can plug the diagnostic connector with key on/engine off. That will activate all relays and solenoids in vehicle. You can see if the drain valve is even working.
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post #3 of 5 (permalink) Old 07-26-2012, 01:51 PM
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Car Year: 2004
Car Model: Forester XT
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Well, I know it sounds too easy, but FWIW, have you tried disconnecting the Neg. battery terminal and let it set overnight to fully reset the ECU?
Td

'98 S-Sold
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post #4 of 5 (permalink) Old 07-26-2012, 02:06 PM Thread Starter
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Join Date: Jul 2012
Location: Sherwood, OR
Posts: 2
Car Year: 98
Car Model: Imp RS
Transmission: 5 MT
-> ECU has had it's memory cleared by a SSM3.
-> Battery has been out overnight. (Charging, due to leaving lights and such on too long one day)
-> ECU has been swapped with another car in which all 8 systems were "ready". (Had one available, why not give it a try?)

Car is overdue for registration, trip permit running out, need to get through DEQ.

Yeah, too bad it was taken in to test with CEL/MIL light on, now the EVAP system MUST test "ready" in order to pass.

Have not plugged in D check connectors, was not certain on how to force drive-cycle test. I will give that a go later today or tomorrow. I know it needs to see the correct parameters for it complete the EVAP system test, but it has been months of driving...

Drain valve operating, holding pressure as I blow into it while it cycles. (yes, it holds, and releases, etc...)

Hoses to pressure regulator, canister, shut valve, roll valve, drain valve, purge valve, & filter are all clear.

Thanks guys!

L
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post #5 of 5 (permalink) Old 07-26-2012, 02:18 PM
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Car Year: 2003
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Evap monitor needs a couple of drives with 50-75% full tank of gas to make its tests, in my experience.
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