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

DTC detecting condition:

Detected when two consecutive driving cycles with fault occur.

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

Wiring diagram:

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

G12456917

Courtesy of SUBARU OF AMERICA, INC.

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 connector from ECM.
4. Disconnect the connectors from front oxygen (A/F) sensor.
5. Measure the resistance of harness between ECM connector and front oxygen (A/F) sensor connector.
  Connector & terminal
  
  (B136) No. 5 - (B379) No. 2:
  
  (B136) No. 6 - (B379) No. 2:
  
  (B136) No. 18 - (B379) No. 3:
  
  (B136) No. 19 - (B379) No. 4:
Is the resistance less than 1 Ω?

Yes: Go to 2

No: Repair the open circuit of harness between ECM connector and front oxygen (A/F) sensor connector.
CHECK FRONT OXYGEN (A/F) SENSOR .
Measure the resistance between front oxygen (A/F) sensor terminals.

Terminals

No. 1 - No. 2:

Is the resistance less than 2 - 3 Ω?

Yes: Go to 3

No: Replace the front oxygen (A/F) sensor. Ref. to FUEL INJECTION (FUEL SYSTEMS) (STI)>Front Oxygen (A/F) Sensor .
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) (STI)>Front Oxygen (A/F) Sensor .