DTC P0030: Ho2S Heater Control Circuit (Bank 1 Sensor 1)

DTC DETECTING CONDITION:

Two consecutive driving cycles with fault
GENERAL DESCRIPTION < Ref. to DTC P0030 HO2S HEATER CONTROL CIRCUIT (BANK 1 SENSOR 1) , Diagnostic Trouble Code (DTC) Detecting Criteria. >

CAUTION: After repair or replacement of faulty parts, conduct Clear Memory Mode < Ref. to , OPERATION , Clear Memory Mode. > and Inspection Mode < Ref. to , PROCEDURE , Inspection Mode. >.

WIRING DIAGRAM:

Fig 1: DTC P0030 - HO2S Heater Control Circuit (Bank 1 Sensor 1) - Wiring Diagram

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC STEPS (DTC)

Step	Check	Yes	No
1 CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR. Start the engine and warm-up engine. Turn the ignition switch to OFF. Disconnect the connectors from ECM and front oxygen (A/F) sensor. Measure the resistance of harness between ECM and front oxygen (A/F) sensor connector. Connector & terminal (B134) No. 2 - (B262) No. 6: (B134) No. 3 - (B262) No. 6:	Is the resistance less than 1 Ω?	Go to step 2 .	Repair the open circuit in harness between ECM and front oxygen (A/F) sensor connector.
2 CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR. Measure the resistance of harness between ECM and front oxygen (A/F) sensor connector. Connector & terminal (B134) No. 33 - (B262) No. 3: (B134) No. 26 - (B262) No. 1:	Is the resistance less than 1 Ω?	Go to step 3 .	Repair the open circuit in harness between main relay and front oxygen (A/F) sensor connector.
3 CHECK HARNESS BETWEEN A/F AND OXYGEN SENSOR RELAY AND FRONT OXYGEN (A/F) SENSOR CONNECTOR. Measure the resistance of harness between main relay and front oxygen (A/F) sensor connector. Connector & terminal (B327) No. 5 - (B262) No. 4:	Is the resistance less than 1 Ω?	Go to step 4 .	Repair the open circuit in harness between A/F and oxygen sensor relay and front oxygen (A/F) sensor connector.
4 CHECK FRONT OXYGEN (A/F) SENSOR. Measure the resistance between front oxygen (A/F) sensor connector terminals. Terminals No. 1 - No. 6:	Is the resistance less than 5 Ω?	Go to step 5 .	Replace the front oxygen (A/F) sensor. < Ref. to FRONT OXYGEN (A/F) SENSOR . >
5 CHECK POOR CONTACT. Check the poor contact in 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 in ECM or front oxygen (A/F) sensor connector.	Replace the front oxygen (A/F) sensor. < Ref. to FRONT OXYGEN (A/F) SENSOR . >