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Evap canister on '99 Forester

Posted by anthonyg_ma (My Page) on
Mon, Jun 7, 10 at 18:40

I've been seeing a steady MIL illuminated for a few weeks now, so I picked up an inexpensive OBDII reader and pulled a code of 'P0440' from the on-board computer. The gas cap appears to be fine, and tight, so I was hoping to follow along the rest of the EVAP diagnostic and see what's wrong. Any suggestions as to where to look under the hood for the canister?
Thanks in advance!


Follow-Up Postings:

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RE: Evap canister on '99 Forester

I don't know this vehicle well enough to say, but does the emissions decal under the hood yield any info on it?


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RE: Evap canister on '99 Forester

A P0440 is a general evaporative emissions system failure, otherwise knows as a weak vacuum test on some manufacturers. The computer commands the purge valve open with the engine running, the vent valve closed to seal the system and then the computer watches the fuel tank vapor pressure sensor to see if it measures about 8" of water vacuum in the canister and fuel tank. if that level of vacuum cannot be achieved, the system cannot test itself for leaks, and that results in the P0440.


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