DTC P0457 Evaporative Emission Control System Leak Detected (Fuel Cap Loose/Off): Wiring Diagram

Fig 1: Evaporative Emission Control System - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK FUEL FILLER CAP  . Turn the ignition switch to OFF. Check the fuel filler cap. NOTE: The DTC is stored in memory if fuel filler cap is or was loose or if the cap chain has caught while tightening.	Is the fuel filler cap tightened securely?	Go to step 2  .	Tighten fuel filler cap securely.
2 CHECK FUEL FILLER CAP  .	Is the fuel filler cap genuine?	Go to step 3  .	Replace with a genuine fuel filler cap.
3 CHECK FUEL FILLER PIPE GASKET  .	Is there any damage to the seal between fuel filler cap and fuel filler pipe?	Repair or replace the fuel filler cap and fuel filler pipe. Ref. to FUEL FILLER PIPE .	Go to step 4  .
4 CHECK DRAIN VALVE OPERATION  . Install the delivery (test) mode fuse. Turn the ignition switch to ON. Perform operation check for the drain valve using the Subaru Select Monitor. NOTE: Drain valve can be operated using the Subaru Select Monitor. For detailed procedures, refer to "SYSTEM OPERATION CHECK MODE". Ref. to SYSTEM OPERATION CHECK MODE .	Does the drain valve operate?	Go to step 5  .	Replace the drain valve. Ref. to DRAIN VALVE .
5 CHECK OPERATION OF PURGE CONTROL SOLENOID VALVE  . Perform operation check for the purge control solenoid valve using the Subaru Select Monitor. NOTE: Purge control solenoid valve operation can be executed using Subaru Select Monitor. For detailed procedures, refer to "SYSTEM OPERATION CHECK MODE". Ref. to SYSTEM OPERATION CHECK MODE .	Does the purge control solenoid valve operate?	Go to step 6  .	Replace the purge control solenoid valve. Ref. to PURGE CONTROL SOLENOID VALVE .
6 CHECK OPERATION OF PRESSURE CONTROL SOLENOID VALVE  . Perform operation check for the pressure control solenoid valve using the Subaru Select Monitor. NOTE: The pressure control solenoid valve operation can be executed using the Subaru Select Monitor. For detailed procedures, refer to "SYSTEM OPERATION CHECK MODE". Ref. to SYSTEM OPERATION CHECK MODE .	Does the pressure control solenoid valve operate?	Go to step 7  .	Replace the pressure control solenoid valve. Ref. to PRESSURE CONTROL SOLENOID VALVE .
7 CHECK EVAPORATIVE EMISSION CONTROL SYSTEM LINE  . Turn the ignition switch to OFF. Remove the delivery (test) mode fuse.	Is there any disconnection, damage or clogging on the evaporation line?	Repair or replace the evaporation line. Ref. to FUEL DELIVERY, RETURN AND EVAPORATION LINES .	Go to step 8  .
8 CHECK CANISTER  .	Is the canister damaged?	Repair or replace the canister. Ref. to CANISTER .	Go to step 9  .
9 CHECK FUEL TANK  . Remove the fuel tank. Ref. to FUEL TANK .	Is the fuel tank damaged?	Repair or replace the fuel tank. Ref. to FUEL TANK .	Go to step 10  .
10 CHECK ANY OTHER MECHANICAL TROUBLE IN EVAPORATIVE EMISSION CONTROL SYSTEM  .	Are there holes, cracks, clogging, or disconnections, mis-connection of hoses or pipes in evaporative emission control system?	Repair or replace the hoses or pipes.	Repair the poor contact of ECM connector.