ENGINE (DIAGNOSTICS)(H4DO) > Diagnostic Procedure with Diagnostic Trouble Code (DTC)

DTC P0038 HO2S HEATER CONTROL CIRCUIT HIGH (BANK 1 SENSOR 2)

DTC DETECTING CONDITION:

Detected when two consecutive driving cycles with fault occur.

CAUTION:

After repairing or replacing the defective part, perform the Clear Memory Mode and Inspection Mode .

WIRING DIAGRAM:

STEPCHECKYESNO

1.CHECK INPUT SIGNAL OF ECM.

1) Turn the ignition switch to OFF.

2) Measure the voltage between ECM connector and chassis ground.

Connector & terminal

(B135) No. 7 (+) — Chassis ground (−):

Is the voltage 8 V or more?

2.CHECK CURRENT DATA.

1) Repair the short to power supply in the harness between ECM and rear oxygen sensor connector.

2) Turn the ignition switch to ON.

3) Read the data of rear oxygen sensor heater current using the Subaru Select Monitor or general scan tool.

NOTE:

• Subaru Select Monitor

For detailed operation procedure, refer to “READ CURRENT DATA FOR ENGINE”.

• General scan tool

For detailed operation procedure, refer to the general scan tool operation manual.

Is the current 7 A or more?

Replace the ECM.

END.

3.CHECK POOR CONTACT.

Check poor contact of ECM connector.

Is there poor contact in ECM connector?

Repair the poor contact of ECM connector.

END.