DTC P2021: TGV Position Sensor/Switch Circuit Low Bank 2: Notes

DTC detecting condition: 

Immediately at fault recognition

Trouble symptom: 

• Improper idling
• Engine stalls.
• 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 «TGV Position Sensor L» using the Subaru Select Monitor.
   NOTE: For detailed operation procedures, refer to "Read Current Data For Engine". Refer to ENGINE (DIAGNOSTICS) (STI)>SUBARU SELECT MONITOR .

   Is the value of «TGV Position Sensor L» less than 0.2 V?

   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 POWER SUPPLY OF TUMBLE GENERATOR VALVE ASSEMBLY LH. 
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from tumble generator valve assembly LH.
   3. Turn the ignition switch to ON.
   4. Measure the voltage between tumble generator valve assembly LH connector and engine ground.

   Connector & terminal 

   (E51) No. 3 (+) - Engine ground (-):

   Is the voltage 4.5 V or more?

   Yes:  Go to  3.

   No:  Repair the harness and connector.

   NOTE: In this case, repair the following item:

   • Open circuit in harness between ECM connector and tumble generator valve assembly LH connector
   • Poor contact of ECM connector
   • Poor contact of coupling connector
3. CHECK HARNESS BETWEEN ECM AND TUMBLE GENERATOR VALVE ASSEMBLY LH CONNECTOR. 
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from ECM.
   3. Measure the resistance of harness between ECM connector and tumble generator valve assembly LH connector.

   Connector & terminal 

   (B137) No. 10 - (E51) No. 1:

   Is the resistance less than 1 Ω?

   Yes:  Go to  4.

   No:  Repair the harness and connector.

   NOTE: In this case, repair the following item:

   • Open circuit in harness between ECM connector and tumble generator valve assembly LH connector
   • Poor contact of coupling connector
4. CHECK HARNESS BETWEEN ECM AND TUMBLE GENERATOR VALVE ASSEMBLY LH CONNECTOR. 

   Measure the resistance between ECM connector and chassis ground.

   Connector & terminal 

   (B137) No. 10 - Chassis ground:

   Is the resistance 1 MΩ or more?

   Yes:  Go to  5.

   No:  Repair the short circuit to ground in harness between ECM connector and tumble generator valve assembly LH connector.

5. CHECK FOR POOR CONTACT. 

   Check for poor contact of ECM and tumble generator valve assembly LH connector.

   Is there poor contact of ECM or the tumble generator valve assembly LH connector?

   Yes:  Repair the poor contact of ECM or tumble generator valve assembly LH connector.

   No:  Replace the tumble generator valve assembly LH. Refer to FUEL INJECTION (FUEL SYSTEMS) (STI)>TUMBLE GENERATOR VALVE ASSEMBLY .