DTC P0134 O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1): Wiring Diagram

Fig 1: O2 Sensor Circuit No Activity Detected (Bank 1 Sensor 1) - Wiring Schematics

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSIS PROCEDURE CHART

Step	Check	Yes	No
1 CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR  . Turn the ignition switch to OFF. Disconnect the connectors from the ECM and front oxygen (A/F) sensor. Measure the resistance of harness between ECM and front oxygen (A/F) sensor connector. Connector & terminal  (B135) No. 9 - (B379) No. 4:  (B135) No. 8 - (B379) No. 3:	Is the resistance less than 1 Ω?	Go to step 2  .	Repair the open circuit of harness between ECM and front oxygen (A/F) sensor connector.
2 CHECK POOR CONTACT  . Check poor contact of ECM and front oxygen (A/F) sensor connector.	Is there poor contact in ECM or front oxygen (A/F) sensor connector?	Repair the poor contact of ECM or front oxygen (A/F) sensor connector.	Replace the front oxygen (A/F) sensor. Refer to FRONT OXYGEN (A/F) SENSOR .