Wiring Diagram:

Fig 1: DTC P0134 - O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1) -

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC STEPS DTC P0134

Step	Check	Yes	No
1. CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR. Turn ignition switch to OFF. Disconnect connectors from ECM and front oxygen (A/F) sensor connector. Measure resistance of harness between ECM and front oxygen (A/F) sensor connector. Connector & terminal (B136) No. 13 - (E18) No. 1: (B136) No. 22 - (B18) No. 2:	Is the measured value less than 1 Ω?	Go to step 2.	Repair harness and connector. NOTE: In this case, repair the following: Open circuit in harness between ECM and front oxygen (A/F) sensor connector Poor contact in front oxygen (A/F) sensor connector Poor contact in ECM connector
2. CHECK POOR CONTACT. Check poor contact in front oxygen (A/F) sensor connector.	Is there poor contact in front oxygen (A/F) sensor connector?	Repair poor contact in front oxygen (A/F) sensor connector.	Replace front oxygen (A/F) sensor. Ref. to FRONT OXYGEN (A/F) SENSOR .