The common cause of the P0456 code on a Dodge Ram is from a faulty gas cap. But can also be from a leak in the purge valve. I would first check to make sure Your gas cap is tight. If Your cap is tight I would replace it. If the canister purge valve fails and sticks open, it will create a vacuum leak that can affect the engine idle speed and quality. A vacuum leak can also be created if the purge solenoid or any of the hoses that may be attached to it break or become damaged.
Larry A.
April 10, 2020
The common cause of the p0456 code is from a faulty gas cap but can also be from a leak in the purge valve.
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