P0456 but no leak via smoke test (1 Viewer)

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I have the Toyota Four Horsemen lights (Check Engine, Skid, TRAC OFF, VSC OFF). OBD code is P0456 (very small leak). Purge VSV valve is closed and doesn't leak via a vacuum gauge and smoke test. I closed the system by plugging the filter exhaust (beyond the Vent valve, see red line) and ran a smoke test. Smoke test boundary was from the red line to the PCV valve at the front of the car. System passed the smoke test, there was no leak. Anyone encounter this? Could it be the vent valve leaking? How do you command the vent valve to close without a scanner tool? Can you back pin the canister pump module harness?

smoke test boundary.png
 
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It’s not the gas cap. New o-ring, then new toyota cap. and there was no smoke Coming from it. Car is new to us. This DTC has been here since we bought it.
 
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BMThiker

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See if you can find someone (a tech or a friend) with TechStream software. That might give more details than the average scan tool.
 

BMThiker

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Ha! I copied this from that conversation @iwashmycar linked to:

I can't remember if it was started in '05 or '06 for the 4th gens, but if you have a Techstream you can initiate a self-test of the system as those canisters have a calibrated orifice and will do an automatic self-test. Additionally you can use either a Techstream or a Toyota capable scantool to initiate an EVAP test and watch the vacuum readings on the scantool to essentially do what you're doing as well.

Just some food for thought if you have a scantool and find yourself having EVAP issues.
 
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The 4Runner thread was enlightening, but I am not positive of the pinout on the harness. When I have a moment I can pull the canister and see if I can isolate the vent valve. I think it is the vent valve or the pressure sensor, both of which reside in or attached to the canister module.
 

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