DTC P0098: Intake Air Temperature Sensor 2 Circuit High Bank 1: Notes

DTC detecting condition: 

Immediately at fault recognition

Trouble symptom: 

• Improper idling
• Poor driving performance

Wiring diagram: 

Engine Electrical System Refer to WIRING SYSTEM>ENGINE ELECTRICAL SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK CURRENT DATA. 
   1. Start the engine.
   2. Read the value of «IAT Sensor #12» using the Subaru Select Monitor or a general scan tool.
   NOTE:

   • Subaru Select Monitor

     For detailed operation procedures, refer to "Current Data Display For Engine". Refer to ENGINE (DIAGNOSTICS) (EXCEPT FOR STI)>SUBARU SELECT MONITOR .

   • General scan tool

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

   Is the value in «IAT Sensor #12» less than -40°C (-40°F)?

   Yes:  Go to  2.

   No:  Even if DTC is detected, the circuit has returned to a normal condition at this time. Reproduce the failure, and then perform the diagnosis again.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
2. CHECK FOR POOR CONTACT. 

   Check for poor contact of ECM and manifold absolute pressure and intake air temperature sensor connector.

   Is there poor contact of ECM or manifold absolute pressure and intake air temperature sensor connector?

   Yes:  Repair the poor contact of ECM or manifold absolute pressure and intake air temperature sensor connector.

   No:  Go to  3.

3. CHECK HARNESS BETWEEN ECM AND MANIFOLD ABSOLUTE PRESSURE AND INTAKE AIR TEMPERATURE SENSOR CONNECTOR. 
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from ECM.
   3. Disconnect the connector from the manifold absolute pressure and intake air temperature sensor.
   4. Measure the resistance of harness between ECM connector and the manifold absolute pressure and intake air temperature sensor connector.

   Connector & terminal 

   (E158) No. 25 - (E124) No. 1:

   (E159) No. 27 - (E124) No. 2:

   Is the resistance less than 1 Ω?

   Yes:  Go to  4.

   No:  Repair the open circuit of the harness between the ECM connector and the manifold absolute pressure & intake air temperature sensor connector.

4. CHECK HARNESS BETWEEN ECM AND MANIFOLD ABSOLUTE PRESSURE AND INTAKE AIR TEMPERATURE SENSOR CONNECTOR. 
   1. Connect all connectors.
   2. Turn the ignition switch to ON.
   3. Measure the voltage between ECM connector and engine ground.

   Connector & terminal 

   (E158) No. 25 (+) - Engine ground (-):

   Is the voltage 5 V or more?

   Yes:  Repair the short circuit to power in harness between ECM connector and the manifold absolute pressure and intake air temperature sensor connector.

   No:  Replace the manifold absolute pressure and intake air temperature sensor. Refer to FUEL INJECTION (FUEL SYSTEMS) (EXCEPT FOR STI)>MANIFOLD ABSOLUTE PRESSURE AND INTAKE AIR TEMPERATURE SENSOR .