I have a 2008 Infiniti FX35. The "service engine soon" light went on, so I took it to the dealer, who replaced a fuel line sensor. The light was off when I left the dealers.

SOURCE: Fuel door indicator light remains on.

You may have one of the following.

A loose gas cap - remove cap and re-tighten again to see if light goes out (may take a while before light goes out)

A faulty gas cap - replace with a new one (shouldn't have failed yet if your car's only a year old)

A faulty fuel sensor only if your fuel level also shows as low (shouldn't have failed yet if your car's only a year old)

There's a vacuum leak somewhere (this would also trigger a check engine light)

SOURCE: 2006 Saturn Relay Check Engine Light

PO455 is a large evaporative fuel leak. A bad fuel cap is ONE of the things that COULD be the problem. Fuel system cleaning only lightened your wallet. Reading your post is confusing. Did all this start AFTER the Valvoline Wallet Flushing? If so , they left something loose or disconnected. I would find a qualified repair shop to fix the problem, and if it has anything to do with what Valvoline did, make them pay the bill.

SOURCE: Just went to drive my

yes, but you will not have traction control available. The lights mean that trouble codes have been set. If you are worried about driving a long distance to a dealership, any major auto parts store will be able to read out the codes for free and even reset the lights if you wish.

SOURCE: Tighten gas cap and then

Doesn't completely sound like a fuel pump problem...sounds like a vacuum line problem .... check your pcv ...and vacuum lines and when was your fuel filter last changed and how many miles are on the car...your fuel pressure regulator solenoid needs to be dry on the vacuum side too...diaphram could be leaking but if you can't find an obvious problem I would definiately find a qualified mechanic to dive into it...do you have access to a scan tool to read the trouble codes?

SOURCE: service engine soon light came

One of the most common causes, is blockage in the venting system from fuel entering the vent lines and into the charcoal canister, the fuel gets absorbed by the charcoal canister causing it to swell and block vent lines. the gas tank contains both fuel and air. when you fill it up the gas displaces the air and the air has to go somewhere. but the air that is displaced is full of gas vapor so the gas vapor goes to the vent lines and into the charcoal canister, when the charcoal canister swells up it prevents the air from escaping the tank, canister could be clogged,canister filter may need replacement,electrical connection to the close valve may be open,canisterf might be damaged,purge valve from canister might be clogged,vent hoses might be clogged, the vent hose could be clogged, or the vent hose may have a kink. all this is caused by overfilling the gas tank, getting that last drop of gas in the neck of the fill tube.
good luck!