DTC P1155 O2 Sensor Circuit Range/Performance (High) (Bank 2 Sensor 1): Wiring Diagram

Fig 1: HO2S (Bank 1 Sensor 1) - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK FRONT OXYGEN (A/F) SENSOR CONNECTOR AND COUPLING CONNECTOR.	Has water entered the connector?	Completely remove any water inside.	Go to step 2.
2 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 between ECM and chassis ground. Connector & terminal  (B135) No. 8 - Chassis ground:  (B135) No. 20 - Chassis ground:	Is the resistance 1 MΩ or more?	Go to step 3.	Repair the ground short circuit of harness between ECM and front oxygen (A/F) sensor connector.
3 CHECK OUTPUT SIGNAL FOR ECM.  Connect the connector to ECM. Turn the ignition switch to ON. Measure the voltage between ECM and chassis ground. Connector & terminal  (B135) No. 8 (+) - Chassis ground (-):	Is the voltage 4.5 V or more?	Go to step 5.	Go to step 4.
4 CHECK OUTPUT SIGNAL FOR ECM.  Measure the voltage between ECM and chassis ground. Connector & terminal  (B135) No. 20 (+) - Chassis ground (-):	Is the voltage 4.95 V or more?	Go to step 5.	Replace the front oxygen (A/F) sensor. Ref. to FRONT OXYGEN (A/F) SENSOR .
5 CHECK OUTPUT SIGNAL FOR ECM.  Measure the voltage between ECM and chassis ground. Connector & terminal  (B135) No. 8 (+) - Chassis ground (-):  (B135) No. 20 (+) - Chassis ground (-):	Is the voltage 8 V or more?	Repair the short circuit of harness to power supply between ECM and front oxygen (A/F) sensor connector. After repair, replace the ECM. Ref. to ENGINE CONTROL MODULE (ECM) .	Repair the poor contact of ECM connector.