Its a common winter cold up here or is this a code. Usually is set at a steady speed, ECU gets bored and decides to run an evaporative emissions test. A normally vent valve mounted at the rear of the tank closes, and the purge valve by the engine opens to the intake manifold.
This draws a vacuum from the tank that the pressure sensor, actually more of a lack of pressure, a vacuum should cause its reading to shoot up to a volt, if it doesn't after a given time period, that code is set.
So whats the problem, the sensor, or a vacuum leak someplace? Most common is a loose gas cap, around here in the winter with all that salt slush, this gets into the canister all in a very stupid location mounted by the gas tank. Would love to meet the people that decided to put it back there in a dark alley. Carbon gets soaked with water, gets into the vent valve, and won't let it close.
Have to tell you these young kids designing our vehicles are complete idiots, for years that canister was mounted high on the fire wall along with the vent valve. Can't even believe that guys that call them selves engineers would even do something like this but does save a hose and you have those a$$hole bean counters.
Yes I hope you are ready this for the grief you are causing the consumers. Have an emission test up here also ran by even more idiots and if that code is set, you don't pass. Have to get your vehicle in a warm spot to dry out, not easy if you live in an apartment building, a kid in college and don't have any extra money.
You can realized I am frustrated with this stupid problem, already getting robbed to death with tuition payments skyrocketing because they claim all the money is for a stupid war, crooks around the university charge outrageous rents for building that should have been condemned a long time ago, then you have these kind of vehicles on top of that. If that carbon canister is shot because they dump loads of salt on sand, that's another 170 bucks out of your pocket and this is DIY.
Also problems with the filler hose, can't run a decent pipe, using rubber hoses for links, rust builds up on the inside. If lucky, the vent valve is frozen, can thaw that out and hope it good again, and it doesn't freeze up again so your kid can pass that emissions test.
Can also have a leak in any of the three fuel lines between the tank, use to be only one, now three, one for the fuel, another for the fuel return, need that to keep fuel flowing in that in tank fuel pump, dang thing is made so cheap, will burn up without fuel flow to cool it, than a vent line for the evaporative system.
Cruze cut that down to two, because the moved the fuel regulator back into the tank, with even a very minor leak, would get a code because air is far less dense than gas, but still have that vent line that doesn't carry fuel.
Kind of a trade off, one less line to check, but if your fuel regulator goes bad, instead of around 30 bucks for a new one, part of the fuel pump assembly that cost 250 bucks to replace it with a ton of labor to drop the tank.
So what is your problem, vacuum sensor, or a minor leak someplace? Don't know until you check, some use a smoke test, feel this is kind of dump. I energize the vent valve to close it, adapt a gas cap to a monitored vacuum pump, while monitoring that sensor output. Also, if that vacuum does not hold, you have a leak, someplace, anywhere between the gas filler tube to the front of the engine.
Does this fuel evaporative system really work? I don't feel so, major source of fuel evaporation was the carburetor bowl itself. When they got rid of that, think that should have been enough, but the EPA sure didn't think so. But still doesn't solve the problem if you have a fuel injector leak.
And is running unshielded wires your problem or the vehicle manufacturers problem? Not only unprotected from varmints, but also road salt. And you wonder why we have problems.
Ha, you got me started again. But fuel evaporative was far less of a problem when the components were mounted high above on the firewall, but sure is a problem now.