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The P0455 is a Evap gross leak.
I would first check the gas cap and make sure that is on properly. If not on properly, that could have caused the code P0455
If the gas cap is on properly, then it's most likely possible the vent control valve is stuck open.
As for the P0325, that is the knock sensor
Is the truck due for inspection any time soon?
im working on it and i like to try to fix this.also darn gas cap on right.i was wondering if they both relate some how
No they are not both related at all
The knock sensor won't turn on the Service Engine Soon light, and you most likely find that code when some other fault happens that turns on the light for you to scan it
If the gas cap is tight, then the problem is most likely the vent control valve.
This code and the vent control valve are part of the evap system.
This will not cause the truck to run bad, but can keep the truck from passing inspection if due.