Man, how does that thing get loose after 3/4 of a tank? Had this happen on my way to work today... time to clear that sucka.

 

Man this topic has saved me time and money!
Just came back from AutoZone with the 1456 code.
Light came on last nite on the way to work, and I realized this morning that it could have been the fuel cap- I always make sure to tighten it to '3 clicks' but when I checked it before going to AutoZone, it was as loose!
Do you guys think the weather has anything to do with the cap loosening itself?

 

how about this... i have this code, and cap IS tight. ive had this code for about a year and a half now... i know, i know... i replaced the gascap, ive cleared it numerous times... it always comes back... mine actually has something wrong with it because my cap doesnt hiss when you take it off. any ideas?

 

Wow, I forgot I had even posted this

Now when I fill my tank up, I tighten it squeezing the outside of the cap so it wont click. It seems to tighten better and I dont get that code anymore.

I got that code 2 or 3 times after I had originally posted this thread, and I think they happened during summer so it seems like the hot weather has something to do with it as Ultimate Combination mentioned.