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Home >> Subaru >> 2017 >> Forester 2.0XT Touring >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 16 (Engine Control System (Diagnostics) (P000A To P015B) (H4DO)) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0030 A/F/O2 Heater Control Circuit Bank 1 Sensor 1 >> Notes

DTC P0030 A/F/O2 Heater Control Circuit Bank 1 Sensor 1: Notes

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

DTC detecting condition: 

Detected when two consecutive driving cycles with fault occur.

CAUTION:

Wiring diagram: 

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

Fig 1: A/F/O2 Heater Control Circuit Bank 1 Sensor 1 - Wiring Diagram
G11272679Courtesy of SUBARU OF AMERICA, INC.
  1. CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR. 
    1. Start and warm up the engine.
    2. Turn the ignition switch to OFF.
    3. Disconnect the connectors from front oxygen (A/F) sensor.
    4. Disconnect the connector from ECM.
    5. Measure the resistance of harness between ECM connector and front oxygen (A/F) sensor connector.

    Connector & terminal 

    (B136) No. 5 - (E24) No. 1: Oxygen sensor heater characteristic (bank 1 sensor 1)

    (B136) No. 19 - (E24) No. 3:

    (B136) No. 18 - (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
  2. CHECK FRONT OXYGEN (A/F) SENSOR. 

    Measure the resistance between front oxygen (A/F) sensor terminals.

    Terminals 

    No. 1 -No. 2:

    Is the resistance 2 - 3 Ω?

  3. 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?