Wiring Diagram:

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

Fig 1: Wiring Diagram - DTC P0452 Evaporative Emission Control System Pressure Sensor Low Input

G03829050

Courtesy of SUBARU OF AMERICA, INC.

DTC P0452 DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1. CHECK CURRENT DATA. Turn ignition switch to OFF. Remove the fuel filler cap. Install the fuel filler cap. Turn ignition switch to ON. Read the data of fuel tank pressure sensor signal using Subaru Select Monitor. NOTE: Subaru Select Monitor For detailed operation procedure, refer to "READ CURRENT DATA FOR ENGINE". < Ref. to , SUBARU SELECT MONITOR . >	Is the measured value less than -2.8 kPa (-21.0 mmHg, -0.827 inHg)?	Go to step 2.	The malfunction indicator light may light up, however, the circuit is returned to the normal status at the moment.
2. CHECK POWER SUPPLY TO FUEL TANK PRESSURE SENSOR. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B136) No. 16 (+) - Chassis ground (-):	Is the voltage more than 4.5 V?	Go to step 4.	Go to step 3.
3. CHECK POWER SUPPLY TO FUEL TANK PRESSURE SENSOR. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B136) No. 16 (+) - Chassis ground (-):	Does the voltage change by shaking the ECM harness and connector?	Repair poor contact in ECM connector.	Contact SOA Service Center.
4. CHECK INPUT SIGNAL FOR ECM. Measure the voltage between ECM and chassis ground. Connector & terminal (B136) No. 21 (+) - Chassis ground (-):	Is the voltage less than 0.2 V?	Go to step 6.	Go to step 5.
5. CHECK INPUT SIGNAL FOR ECM. (USING SUBARU SELECT MONITOR.) Read the data of fuel tank pressure sensor signal using Subaru Select Monitor. NOTE: Subaru Select Monitor For detailed operation procedure, refer to "READ CURRENT DATA FOR ENGINE". < Ref. to , SUBARU SELECT MONITOR . >	Does the measured value change by shaking the ECM harness and connector?	Repair poor contact in ECM connector.	Go to step 6.
6. CHECK HARNESS BETWEEN ECM AND COUPLING CONNECTOR IN REAR WIRING HARNESS. Turn ignition switch to OFF. Remove the rear seat cushion. Separate rear wiring harness and fuel tank cord. Turn ignition switch to ON. Measure the voltage between rear wiring harness connector and chassis ground. Connector & terminal (R15) 7 (+) - Chassis ground (-):	Is the voltage more than 4.5 V?	Go to step 7.	Repair harness and connector. NOTE: In this case, repair the following: Open circuit in harness between ECM and rear wiring harness connector Poor contact in coupling connector
7. CHECK HARNESS BETWEEN ECM AND COUPLING CONNECTOR IN REAR WIRING HARNESS. Turn ignition switch to OFF. Disconnect the connector from ECM. Measure the resistance of harness between ECM and rear wiring harness connector. Connector & terminal (B136) 35 - (R15) No. 4:	Is the resistance less than 1 Ω?	Go to step 8.	Repair harness and connector. NOTE: In this case, repair the following: Open circuit in harness between ECM and rear wiring harness connector Poor contact in coupling connector Poor contact in joint connector
8. CHECK HARNESS BETWEEN ECM AND COUPLING CONNECTOR IN REAR WIRING HARNESS. Measure the resistance of harness between rear wiring harness connector and chassis ground. Connector & terminal (R15) No. 4 (+) - Chassis ground:	Is the resistance more than 1 MΩ?	Go to step 9.	Repair short circuit to ground in harness between ECM and rear wiring harness connector.
9. CHECK FUEL TANK CORD. Disconnect the connector from fuel tank pressure sensor. Measure the resistance of fuel tank cord. Connector & terminal (R57) 7 - (R47) No. 3:	Is the resistance less than 1 Ω?	Go to step 10.	Repair open circuit in fuel tank cord.
10. CHECK FUEL TANK CORD. Measure the resistance of fuel tank cord. Connector & terminal (R57) No. 4 - (R47) No. 1:	Is the resistance less than 1 Ω?	Go to step 11.	Repair open circuit in fuel tank cord.
11. CHECK FUEL TANK CORD. Measure the resistance of harness between fuel tank pressure sensor connector and engine ground. Connector & terminal (R47) No. 2 - Chassis ground:	Is the resistance more than 1 MΩ?	Go to step 12.	Repair short circuit to ground in fuel tank cord.
12. CHECK FOR POOR CONTACT. Check for poor contact in fuel tank pressure sensor connector.	Is there poor contact in fuel tank pressure sensor connector?	Repair poor contact in fuel tank pressure sensor connector.	Replace the fuel tank pressure sensor. < Ref. to FUEL TANK PRESSURE SENSOR . >