Code P0456. Part in fuel tank cracked. what is it?

Anything cracked in the fuel system even if it is not a source of a fuel leak will allow fuel vapor into the atmosphere and in so doing be an emission failure. The system checks itself by having a vacuum draw in the fuel tank under certain conditions and if the tank can't hold a vacuum the system is deemed by the computer in your car to have a leak. You would have to identify the part that is cracked on a parts slide at the dealership. A lot of dealers are helpful and can fax or email the parts slide to you so you identify the correct part. http://www.obd-codes.com/p0456

this obd2 trouble code table can help you understand the meaning of code. http://www.chinasinoy.com/service/how-to-understand-trouble-codes-37.html for this code, you can try: First, using a scan tool activate the vent solenoid, sealing the system. Then monitor the fuel tank pressure (FTP) sensor. If the system is sealing properly, the number will stay consistent. If is isn't, the pressure sensor will show that as well. If the system slowly leaks, use a smoke machine and watch for smoke exiting the system at any EVAP component. Any where there is smoke exiting the system, that is the faulty component. Do not pressurize the EVAP system with air pressure. Doing so can damage the purge and vent solenoids in the system.