DTC P0037 Ho2S Heater Control Circuit Low (Bank 1 Sensor 2): Wiring Diagram

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

Engine Electrical System ENGINE TYPE EJ (WITHOUT PUSH BUTTON START) <Ref. to 2.5L TURBO (WITHOUT PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>
Engine Electrical System ENGINE TYPE EJ (WITH PUSH BUTTON START) <Ref. to 2.5L TURBO (WITH PUSH BUTTON START), WIRING DIAGRAM, Engine Electrical System.>

Fig 1: HO2S Heater Control (Bank 1 Sensor 2) - Wiring Diagram (Low)

G10265807

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK POWER SUPPLY TO REAR OXYGEN SENSOR. Turn the ignition switch to OFF. Disconnect the connector from rear oxygen sensor. Turn the ignition switch to ON. Measure the voltage between rear oxygen sensor connector and engine ground. Connector & terminal (T6) No. 2 (+) - Engine ground (-):	Is the voltage 10 V or more?	Go to step 2 .	Repair the power supply line. NOTE: In this case, repair the following item: Open circuit in harness between A/F, oxygen sensor relay and rear oxygen sensor connector Poor contact of A/F, oxygen sensor relay connector Poor contact of coupling connector Malfunction of A/F, oxygen sensor relay
2 CHECK HARNESS BETWEEN ECM AND REAR OXYGEN SENSOR CONNECTOR. Turn the ignition switch to OFF. Disconnect the connector from ECM. Measure the resistance between ECM connector and rear oxygen sensor connector. Connector & terminal (B135) No. 6 - (T6) No. 1:	Is the resistance less than 1 Ω?	Go to step 3 .	Repair the harness and connector. NOTE: In this case, repair the following item: Open circuit in harness between ECM connector and rear oxygen sensor connector Poor contact of coupling connector
3 CHECK GROUND CIRCUIT FOR ECM. Measure the resistance of harness between ECM connector and chassis ground. Connector & terminal (B134) No. 3 - Chassis ground: (B134) No. 4 - Chassis ground: (B134) No. 6 - Chassis ground: (B137) No. 1 - Chassis ground: (B137) No. 3 - Chassis ground:	Is the resistance less than 5 Ω?	Go to step 4 .	Repair the harness and connector. NOTE: In this case, repair the following item: Open circuit of harness between ECM connector and engine ground Poor contact of ECM connector Poor contact of coupling connector
4 CHECK REAR OXYGEN SENSOR. Measure the resistance between rear oxygen sensor terminals. Terminals No. 1 - No. 2:	Is the resistance 5 - 6.4 Ω?	Repair the poor contact of ECM connector.	Replace the rear oxygen sensor. <Ref. to REAR OXYGEN SENSOR .>