2013 Subaru TribecaFACTORY OEM SERVICE PROCEDURE

Diagnostic Procedure

DIAGNOSTIC PROCEDURE

Step Check Yes No
1 CHECK REAR OXYGEN SENSOR DATA. 
  1. Warm up the engine until engine coolant temperature is higher than 75°C (167°F), and keep the engine speed at 3, 00 rpm. (2 minutes maximum)
  2. Read the value of «Front O2 Sensor #2» using the Subaru Select Monitor or a general scan tool.
NOTE:
  • Subaru Select Monitor

    For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Refer to SUBARU SELECT MONITOR . >

  • General scan tool

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

 Is the value of «Front O2 Sensor #2» 0.490 V or more? Go to step 6  . Go to step 2  .
2 CHECK REAR OXYGEN SENSOR DATA. 
  1. Warm up the engine until engine coolant temperature is higher than 75°C (167°F), and rapidly reduce the engine speed from 3, 00 rpm.
  2. Read the value of «Front O2 Sensor #2» using the Subaru Select Monitor or a general scan tool.
NOTE:
  • Subaru Select Monitor

    For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Refer to SUBARU SELECT MONITOR . >

  • General scan tool

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

 Is the value of «Front O2 Sensor #2» 0.250 V or less? Go to step 6  . Go to step 3  .
3 CHECK REAR OXYGEN SENSOR CONNECTOR AND COUPLING CONNECTOR.  Has water entered the connector? Completely remove any water inside. Go to step 4  .
4 CHECK HARNESS BETWEEN ECM AND REAR OXYGEN SENSOR CONNECTOR. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from ECM and rear oxygen sensor.
  3. Measure the resistance of harness between ECM and rear oxygen sensor connector.

    Connector & terminal 

    (B135) No. 28 - (E25) No. 3: 

    (B135) No. 30 - (E25) No. 4: 

 Is the resistance less than 1 Ω? Go to step 5  . Repair the harness and connector.
NOTE: In this case, repair the following item:
  • Open circuit in harness between ECM and rear oxygen sensor connector
  • Poor contact of coupling connector
5 CHECK HARNESS BETWEEN ECM AND REAR OXYGEN SENSOR CONNECTOR. 
  1. Connect the connector to ECM.
  2. Turn the ignition switch to ON.
  3. Measure the voltage between rear oxygen sensor connector and chassis ground.

    Connector & terminal 

    (E25) No. 3 (+) - Chassis ground (-): 

 Is the voltage 0.2 - 0.5 V? Replace the rear oxygen sensor. Refer to REAR OXYGEN SENSOR . > Repair the harness and connector.
NOTE: In this case, repair the following item:
  • Open circuit in harness between ECM and rear oxygen sensor connector
  • Poor contact of ECM connector
  • Poor contact of coupling connector
6 CHECK EXHAUST SYSTEM. 
Check exhaust system parts.
NOTE: Check the following items.
  • Looseness and improper fitting of exhaust system parts
  • Damage (crack, hole etc.) of parts
  • Loose part and improper installation between front oxygen (A/F) sensor and rear oxygen sensor
 Is there any fault in exhaust system? Repair or replace faulty parts. Replace the rear oxygen sensor. Refer to REAR OXYGEN SENSOR . >
Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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