Hi everyone
I am a tech at a Dodge Dealer, been trying to fix an ongoing problem with
my
daughter's 2000 Nissan Altima, 4 cylinder sedan. It keeps turning on the
check engine light with fault code P0440 "Large Leak Detected" relating to
the evap system. At first, the code would be accompanied by P1448
"cannister
vent valve stuck open" code but, after I replaced the (expensive) valve,
located at the va**** cannister, the only recurring code is "Large Leak". I
replaced the gas cap, and I used a smoke generator machine to test for
actual leaks, but found none. I tested the "Purge Volume Control Valve" in
the engine compartment and found it to be operational. I verified that the
proper voltage is available at all the little doo-hickeys and solenoids
under the vehicle that are involved in the evap system, leaving only the
ECU
to supply ground for the tests to run - but have no idea if it is because
I
don't have a proper Nissan scan tool to force tests. I know the damn thing
*can* pass the Large Leak test because at one point it turned its own
light
off for a couple of days.
Anyway, the car thinks it has a large evap leak, but as far as I can tell
it
doesn't, any ideas or prior experience with a problem like this greatly
appreciated, thanks.
Raddion
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