How do you rest this? I have a code P1456. The dealer replaced the gas cap and reset the check engine light. After 183 miles the light came back on and now the dealers wants more money to do further diagnosis?
On the mainland, Advance Auto Parts and AutoZone used to read and clear your codes for free. As of late in my area, they will still read your codes but will not clear them for your. Occasionally, they will let you use their reader yourself which provides you the opportunity to clear them. Or...you can purchase an OBD reader for less than the likely dealer fee for reading and clearing the codes and then you can always read and clear them yourself.
I recommend purchasing a reader, even an inexpensive one. Just make sure that it will clear the codes also. This has proven to be a valuable tool for me over the years.
P1456 is a leak in the fuel tank system. There are many things that can cause the problem. The best way to troubleshoot it is with a pressure test but that takes time and you can't blame the mechanic for charging for his time. Are you sure you are tightening the gas cap enough. Most common cause of this problem is not installing the gas cap tight enough. Six clicks at least.
I had this code at one point. A new cap did not fix the issue but is the first step. What did fix it is sealing the fill pipe like mentioned in a thread on here. Search that code and look for one with pictures attached.