Fixing a trouble code P0452

I have an annoying code that comes and goes P0452, Evaporative Emission Control System Pressure Sensor Low Input, a friend said replace the vent solenoid, did that(with a gm part) reset codes, and it lasted one day, service engine soon light back on, what's the next step?

I have an annoying code that comes and goes P0452, Evaporative Emission Control System Pressure Sensor Low Input, a friend said replace the vent solenoid, did that(with a gm part) reset codes, and it lasted one day, service engine soon light back on, what's the next step?

I had that code for a while for some reason it went away on its own

What is the reference voltage at the tank pressure sensor?

I haven't checked it, what's the proper procedure for doing this, I don't have a manual.

i have A 99 OLDS BRAVADA things starting to be a headache i went out one morning started it up went back in the house to grab something came back out and it was off tryed to restart it and all it did was crank but wont start.today i ran a code check and got p0452 i called auto zone and they said try replacing the gas cap and check my vacuum lines.....any thoughts on that?