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

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

DTC DETECTING CONDITION:

Two consecutive driving cycles with fault
GENERAL DESCRIPTION < Ref. to DTC P0037 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 2) , 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: Wiring Diagram - DTC P0037 HO2S Heater Control Circuit Low (Bank 1 Sensor 2)

Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE (DTC P0037)

Step	Check	Yes	No
1 CHECK GROUND CIRCUIT FOR ECM. Turn the ignition switch to OFF. Disconnect the connector from ECM. Measure the resistance of harness between ECM connector and chassis ground. Connector & terminal (B135) No. 1 - Chassis ground: B135 No. 4 - Chassis ground:	Is the resistance less than 5 ?	Go to step 2.	Repair the harness and connector. NOTE: In this case, repair the following: Open circuit in harness between ECM and engine ground cable Poor contact in ECM connector Poor contact in coupling connector
2 CHECK HARNESS BETWEEN ECM AND REAR OXYGEN SENSOR. Disconnect the connector from rear oxygen sensor. Measure the resistance between ECM connector and chassis ground. Connector & terminal (B135) No. 2 - Chassis ground:	Is the voltage more than 1 M?	Go to step 3.	Repair the ground short circuit in harness between ECM and rear oxygen sensor connector.
3 CHECK HARNESS BETWEEN ECM AND REAR OXYGEN SENSOR. Measure the resistance between ECM connector and chassis ground. Connector & terminal (B135) No. 2 - Chassis ground:	Does the resistance change by shaking the ECM harness and connector?	Repair the poor contact in ECM connector.	Go to step 4.
4 CHECK POWER SUPPLY TO REAR OXYGEN SENSOR. Connect the connector to ECM. Turn the ignition switch to ON. Measure the voltage between rear oxygen sensor connector and chassis ground. Connector & terminal (T6) No. 2 (+) - Chassis ground (-):	Is the voltage more than 10 V?	Go to step 5.	Repair the power supply line. NOTE: In this case, repair the following: Open circuit in harness between main relay and rear oxygen sensor connector Poor contact in rear oxygen sensor connector Poor contact in coupling connector
5 CHECK REAR OXYGEN SENSOR. Turn the ignition switch to OFF. Measure the resistance between rear oxygen sensor connector terminals. Terminals No. 1 - No. 2:	Is the resistance less than 30 ?	Repair the harness and connector. NOTE: In this case, repair the following: Open circuit in harness between rear oxygen sensor and ECM connector Poor contact in rear oxygen sensor connector Poor contact in ECM connector Poor contact in coupling connector	Replace the rear oxygen sensor. < Ref. to REAR OXYGEN SENSOR . >