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 OPERATION , Clear Memory Mode, and Inspection Mode Ref. to PROCEDURE , Inspection Mode.
Use the check board when measuring the ECM terminal voltage and resistance.

Wiring diagram:

Engine Electrical System Ref. to WIRING DIAGRAM , Engine Electrical System.

Fig 1: A/F And O2 Heater Control Circuit Bank 1 Sensor 1 - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

Step	Check	Yes	No
1 CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR. Start and warm up the engine. Turn the ignition switch to OFF. Disconnect the connector from ECM. Disconnect the connectors from front oxygen (A/F) sensor. Measure the resistance of harness between ECM connector and front oxygen (A/F) sensor connector. Connector & terminal (B158) No. 5 - (E24) No. 1: (B158) No. 46 - (E24) No. 3: (B158) No. 33 - (E24) No. 4:	Is the resistance less than 1 Ω?	Go to step 2	Repair the open circuit of harness between ECM connector and front oxygen (A/F) sensor 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?	Go to step 3	Replace the front oxygen (A/F) sensor. Ref. to FRONT OXYGEN (A/F) SENSOR
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?	Repair the poor contact of ECM or front oxygen (A/F) sensor connector.	Replace the front oxygen (A/F) sensor. Ref. to FRONT OXYGEN (A/F) SENSOR