Wiring Diagram:

WARNING: This page is about a different variant/trim than selected.

Fig 1: Wiring Diagram - DTC P0400 Exhaust Gas Recirculation Flow

G03829044

Courtesy of SUBARU OF AMERICA, INC.

DTC P0400 DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1. CHECK FOR ANY OTHER DTC ON DISPLAY.	Is any other DTC displayed?	Inspect DTC using "List of Diagnostic Trouble Code (DTC)". < Ref. to , LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . >	Go to step 2.
2. CHECK CURRENT DATA. Start the engine. Read data of intake manifold absolute pressure signal using Subaru Select Monitor or OBD-II general scan tool. NOTE: Subaru Select Monitor For detailed operation procedure, refer to "READ CURRENT DATA FOR ENGINE". < Ref. to , SUBARU SELECT MONITOR . > OBD-II general scan tool For detailed operation procedure, refer to the OBD-II general scan tool instruction manual .	Is the measured value more than 53.3 kPa (400 mmHg, 15.75 inHg)?	Make sure that EGR valve, manifold pressure sensor and throttle body are securely installed.	Go to step 3.
3. CHECK POWER SUPPLY TO EGR SOLENOID VALVE. Disconnect connector from EGR solenoid valve. Turn ignition switch ON. Measure voltage between EGR solenoid valve and engine ground. Connector & terminal (E15) No. 2 - Engine ground: (E18) 5 - Engine ground:	Is the measured value more than 10 V?	Go to step 4.	Repair the open circuit in harness between main relay and EGR solenoid valve connector.
4. CHECK EGR SOLENOID VALVE. Measure resistance between EGR solenoid valve terminals. NOTE: Measure resistance between EGR solenoid valve terminals. Connector & terminal No. 1 - No. 2: No. 3 - No. 2: No. 4 - No. 5: No. 6 - No. 5:	Is the measured value within 20 to 30 Ω?	Go to step 5.	Replace EGR solenoid valve. < Ref. to EGR VALVE . >
5. OUTPUT SIGNAL FROM ECM Turn ignition switch OFF. Connect connectors to ECM and EGR solenoid valve. Turn ignition switch ON. Measure voltage between ECM and chassis ground. Connector & terminal (B134) No. 9 (+) - Chassis ground (-): (B134) No. 10 (+) - Chassis ground (-): (B134) No. 11 (+) - Chassis ground (-): (B134) 8 (+) - Chassis ground (-):	Is the measured value within 0 to 10 V?	Repair poor contact in ECM connector.	Go to step 6.
6. CHECK HARNESS BETWEEN EGR SOLENOID VALVE AND ECM CONNECTOR. Turn ignition switch OFF. Disconnect connector from EGR solenoid valve and ECM. Measure resistance of harness between EGR solenoid valve and ECM connector. Connector & terminal (B134) No. 9 - (E18) No. 4: (B134) No. 10 - (E18) No. 1: (B134) No. 11 - (E18) No. 3: (B134) 8 - (E18) No. 6:	Is the measured value less than 1 Ω?	Go to step 7.	Repair open circuit in harness between ECM and EGR solenoid valve connector. < Ref. to EGR VALVE . >
7. CHECK HARNESS BETWEEN EGR SOLENOID VALVE AND ECM CONNECTOR. Measure resistance of harness between EGR solenoid valve and chassis ground. Connector & terminal (B134) No. 9 - Chassis ground: (B134) No. 10 - Chassis ground: (B134) No. 11 - Chassis ground: (B134) No. 8 - Chassis ground:	Is the measured value more than 1 MΩ?	Go to step 8.	Repair short circuit in harness between main relay and EGR solenoid valve connector.
8. CHECK POOR CONTACT. Check poor contact in ECM and EGR solenoid valve connector.	Is there poor contact in ECM and EGR solenoid valve connector?	Repair poor contact in ECM and EGR solenoid valve connector.	Even if MIL lights up, the circuit has returned to a normal condition at this time.