I have a P0456 code but I was told it came on because I used 87 in my 03 stype when I first bought it. Didn't know it took premium and didn't see the label on the gas door (I know, stupid me but it was extremely code when I bought the car and it was on E). Now a month later, been putting premium in it ever since and the light is still on. I guess it wasn't the gas or is it? Has anyone had this problem before and how the heck do I get the light to reset and see if it goes on again? I have disconnected the battery and left it off for an hour and the light is still on. I have only put about 150 miles on the car since I've been using premium now.

 

It had nothing to do with octane rating of the fuel. Code P0456 means that you might have a loose or defective gas cap seal or more probably a leak somewhere in the evap system.

 

If I get a gas cap from the dealership, will they clear my code?

 

No, not automatically and usually not for free. Have your present cap tested to see if it's actually at fault or start reading all the other possible causes as detailed in the long post on the topic.

 

See xjrguy's reply to your same question in other thread. It's not the gas. May be partially a bad cap but see his reply.