Evap code P0455
November 14th, 2018, 2:03 PM
#1
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Evap code P0455
So I have an Evap code P0455 - large leak detected. when the light initially came on they said replace the gas cap... so I did and the light went away for a while. It came back on and I noticed every time I filled my tank up it wouldn’t wanna start hardly so I replaced the purge solenoid on the front of the engine and the light went away for a while again. Then back again a while later this time the pump would keep cutting off when I was filling up so I replaced the charcoal canister and it solved my problem once again for a while. Well now it’s badk and I also replaced the vent valve solenoid above the spare tire and had it smoke tested there are no leaks so what could be causing this light and it telling me there is a large leak detected?
November 14th, 2018, 10:35 PM
#2
smoke test is for finding leaks...flow test is for determining if a leak is present. uses the same machine but you monitor a flow valve check ball. if no leaks the ball rides under a calibrated value. saying they smoke tested it without monitoring the flow valve makes me question the testing.
depending on the model year...the evap monitor could be looking at fuel tank pressure sensor readings to determine if the system is sealed...for the test the truck will open the purge solenoid, close the vent and monitor the ftps reading... the pressure should drop due to manifold vacuum from the open purge when the engine is running. if no change in the ftps reading...it determines somethings leaking....but it could be a blocked vacuum line, bad sensor etc.
depending on the model year...the evap monitor could be looking at fuel tank pressure sensor readings to determine if the system is sealed...for the test the truck will open the purge solenoid, close the vent and monitor the ftps reading... the pressure should drop due to manifold vacuum from the open purge when the engine is running. if no change in the ftps reading...it determines somethings leaking....but it could be a blocked vacuum line, bad sensor etc.