Wiring Diagram:

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

Fig 1: Wiring Diagram - DTC P1153 O2 Sensor Circuit Range/Performance (High) (Bank1 Sensor1)

G03829067

Courtesy of SUBARU OF AMERICA, INC.

DTC P1153 DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1. CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR. Turn the ignition switch to OFF. Disconnect the connector from ECM. Measure the resistance of harness between ECM connector and chassis ground. Connector & terminal (B134) 26 - Chassis ground:	Is the measured value more than 1 MΩ?	Repair the ground short circuit in harness between ECM and front oxygen (A/F) sensor connector.	Go to step 2.
2. CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR. Measure the resistance of harness between ECM connector and chassis ground. Connector & terminal (B134) No. 33 - Chassis ground:	Is the measured value more than 1 MΩ?	Repair the ground short circuit in harness between ECM and front oxygen (A/F) sensor connector.	Go to step 3.
3. CHECK OUTPUT SIGNAL FOR ECM. Connect the connector to ECM. Turn the ignition switch to ON. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B134) 26 (+) - Chassis ground (-):	Is the measured value more than 4.5 V?	Go to step 4.	Go to step 5.
4. CHECK OUTPUT SIGNAL FOR ECM. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B134) No. 26 (+) - Chassis ground (-):	Is the measured value more than 10 V?	Repair the battery short circuit in harness between ECM and front oxygen (A/F) sensor connector. After repair, replace the ECM. < Ref. to ENGINE CONTROL MODULE (ECM) . >	Repair the poor contact in ECM connector.
5. CHECK OUTPUT SIGNAL FOR ECM. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B134) No. 33 (+) - Chassis ground (-):	Is the measured value more than 4.95 V?	Go to step 6.	Replace the front oxygen (A/F) sensor. < Ref. to FRONT OXYGEN (A/F) SENSOR . >
6. CHECK OUTPUT SIGNAL FOR ECM. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B134) No. 33 (+) - Chassis ground (-):	Is the measured value more than 10 V?	Repair the battery short circuit in harness between ECM and front oxygen (A/F) sensor connector. After repair, replace the ECM. < Ref. to ENGINE CONTROL MODULE (ECM) . >	Repair the poor contact in ECM connector.