P1456 means your gas tank & some other stuff isn't airtight like it should be. That's the code you get when you forget to tighten you gas cap. Reset it by pulling fuse #13 in your passenger door jamb, & see if it comes back.

That works if there really isn't anything wrong. But if there's a real problem (& you haven't fixed it), the light will come back after a day or 2.

There isn't a fuel tank temperature sensor! WTF????

There's a fuel tank PRESSURE sensor, but it's only 1 of about 10 different things that can trigger P1456. There's about 6 pages of procedures in the Helm repair manual for that code. It might just be a disconnected vacuum hose.