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DTC P0037 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 2)

DTC P0037 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 2)

DTC DETECTING CONDITION:


• Two consecutive driving cycles with fault

• GENERAL DESCRIPTION


Important

After repair or replacement of faulty parts, conduct Clear Memory Mode and Inspection Mode .


WIRING DIAGRAM:


CHECK GROUND CIRCUIT OF 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

(B134) No. 6 — Chassis ground:

(B134) No. 7 — Chassis ground:

Is the resistance less than 5 Ω?

Yes


No

• Repair harness and connector.

Note

In this case, repair the following:

• Open circuit in harness between ECM and engine ground terminal

• Poor contact in ECM connector

• Poor contact in coupling connector



CHECK CURRENT DATA.

Start the engine.

Read the data of rear oxygen sensor heater current using Vehicle Diagnostic Interface or OBD-II general scan tool.

Note
• Vehicle Diagnostic Interface

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

• OBD-II scan tool

For detailed operation procedures, refer to the OBD-II General Scan Tool Instruction Manual.


Is the current more than 0.2 A?

Yes

• Repair the connector.

•
Note

In this case, repair the following:

• Poor contact in rear oxygen sensor connector

• Poor contact in rear oxygen sensor connecting harness connector

• Poor contact in ECM connector



No


CHECK OUTPUT SIGNAL FROM ECM.

Start and idle the engine.

Measure the voltage between ECM connector and chassis ground.

Connector & terminal

(B135) No. 2 (+) — Chassis ground (−):

Is the voltage less than 1 V?

Yes


No


CHECK OUTPUT SIGNAL FROM ECM.

Measure the voltage between ECM connector and chassis ground.

Connector & terminal

(B135) No. 2 (+) — Chassis ground (−):

Does the voltage change by shaking the ECM harness and connector?

Yes

Repair poor contact in ECM connector.


No


CHECK OUTPUT SIGNAL FROM ECM.

Disconnect the connector from rear oxygen sensor.

Measure the voltage between ECM connector and chassis ground.

Connector & terminal

(B135) No. 2 (+) — Chassis ground (−):

Is the voltage less than 1 V?

Yes

Replace the ECM.


No

Repair battery short circuit in harness between ECM and rear oxygen sensor connector. After repair, replace the ECM.


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 or chassis ground.

Connector & terminal

(B19) No. 2 (+) — Chassis ground (−):

Is the voltage more than 10 V?

Yes


No

• Repair 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



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 Ω?

Yes

• Repair 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



No

Replace the rear oxygen sensor.