Got this code, and message (check gas cap) on 2014 journey. New gas cap-no help, Purge solenoid vave was removed and checked ok, This valve is located in the left rear back corner of the engine compartment. 1 electrical connection and 2 hoses. Easy to check -open or shut with no leakage shut. Next checked the canister purge valve also called the vent valve or the vapor leak detection pump.This is located under the spare tire-drop spare, and spare tire liner (4- 10 mm nuts. ) Two 10mm bolts hold the canister up and once dropped the valve can be seen. The electrical connector has a red lock tap keeping it locked in. Move tap over and press and it comes off. One hose to remove and the turn counter clockwise to pull out of canister. Mine was shot-stuck open. Replaced it and codes and message cleared. Both valves are available about anywhere. I left the canister in place when I changed the valve.

 

the part you replaced is an esim…. evaporative system integrity monitor. replace the esim fresh air filter while your at it. the fuel tank breathes through the esim and filter during fill ups and fuel pump operation. keep this line clear or you will get hard to fill concerns and possibly concave fuel tanks. Its at the other end of the hose you took off the esim.

p0456 small leak dtc can take up to one week to run the monitor...not at all if the ambient temps are to cold.

 

Thanks for the tip!