DTC P0154: A/F/O2 Sensor Circuit No Activity Detected Bank 2 Sensor 1: Notes

DTC detecting condition:

Immediately at fault recognition

CAUTION: After servicing or replacing faulty parts, perform Clear Memory Mode Ref. to ENGINE (DIAGNOSTICS) (H6DO)>Clear Memory Mode>OPERATION , and inspection mode Ref. to ENGINE (DIAGNOSTICS) (H6DO)>Inspection Mode>PROCEDURE .

Wiring diagram:

Engine Electrical System Ref. to WIRING SYSTEM>Engine Electrical System>WIRING DIAGRAM

Courtesy of SUBARU OF AMERICA, INC.

CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR.
1. Turn the ignition switch to OFF.
2. Disconnect the connector from ECM.
3. Disconnect the connectors from front oxygen (A/F) sensor.
4. Measure the resistance of harness between ECM connector and front oxygen (A/F) sensor connector.
  Connector & terminal
  
  (E158) No. 45 - (E24) No. 3:
  
  (E158) No. 44 - (E24) No. 4:
Is the resistance less than 1 Ω?

Yes: Go to 2

No: Repair the harness and connector.

NOTE: In this case, repair the following item:
- Open circuit in harness between ECM connector and front oxygen (A/F) sensor connector
- Poor contact of coupling connector
CHECK FOR POOR CONTACT.
Check for poor contact of ECM and front oxygen (A/F) sensor connector.

Is there poor contact of ECM or front oxygen (A/F) sensor connector?

Yes: Repair the poor contact of ECM or front oxygen (A/F) sensor connector.

No: Replace the front oxygen (A/F) sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H6DO)>FRONT OXYGEN (A/F) SENSOR