DTC P1456: EVAP Control System - Very Small Leak Or Does Not Operate Properly: Description

This diagnosis detects very small leaks in the EVAP line between fuel tank and EVAP Canister Purge Volume Control Solenoid Valve (EVAP-CPVCSV), using vapor pressure in the fuel tank. The EVAP canister vent control valve is closed to shut EVAP purge line. Vacuum cut valve by-pass valve will then open to clear line between fuel tank and EVAP-CPVCSV. EVAP control system can then monitor pressure inside of fuel tank.

If fuel tank pressure increases, ECM will check for leaks in line between the vacuum cut valve and EVAP-CPVCSV.