Hi,
These are completely separate systems and should be diagnosed separately. The P0456 is for the emission system and the o2 code is part of the exhaust.
The fuel pressure hose is not part of the EVAP system.
I included the testing for each code. Run through this and tell me what you find. I included the tests for a generic scan tool which is what I assume you have. Let me know if you have questions.
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Friday, October 4th, 2019 AT 1:22 PM