The vent valve by the gas tank closes and the canister purge valve opens to allow vacuum to the gas tank to pull a vacuum in the gas tank. Then the fuel tank pressure sensor measures the vacuum being pulled on the gas tank so it can tell if there is a leak in the evap system. The P0455 means there is a vacuum present in the evap system when the ecm didnt command one. Most of the time its caused by the canister purge solenoid being stuck open all the time. Thats why I said to unplug the electrical connector to it remove the vacuum lines to it and blow thru it to see if its stuck open. If its stuck open then to replace it.
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Saturday, November 26th, 2011 AT 12:57 AM