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Home >> Subaru >> 2019 >> Crosstrek Base, Standard Trans >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostics) (Except For HEV) (2 Of 4) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P050A: Cold Start Idle Control System Performance >> Notes

DTC P050A: Cold Start Idle Control System Performance: Notes

1. - 

DTC detecting condition: 

Detected when two consecutive driving cycles with fault occur.

Trouble symptom: 

Wiring diagram: 

Engine Electrical System. Refer to WIRING SYSTEM (IMPREZA MODEL)>ENGINE ELECTRICAL SYSTEM>WIRING DIAGRAM . Refer to WIRING SYSTEM (CROSSTREK MODEL (EXCEPT FOR HEV))>ENGINE ELECTRICAL SYSTEM>WIRING DIAGRAM .

G12400034Courtesy of SUBARU OF AMERICA, INC.
G12399988Courtesy of SUBARU OF AMERICA, INC.
CAUTION: Use the check board when measuring the ECM terminal voltage and resistance. Refer to ENGINE (DIAGNOSTICS) (H4DO (EXCEPT FOR HEV))>GENERAL DESCRIPTION>PREPARATION TOOL>HOW TO USE CHECK BOARD .
NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Refer to ENGINE (DIAGNOSTICS) (H4DO (EXCEPT FOR HEV))>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .
  1. CHECK DTC  .

    Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Refer to ENGINE (DIAGNOSTICS) (H4DO (EXCEPT FOR HEV))>DIAGNOSTIC TROUBLE CODE (DTC) .

    Is DTC other than P050A displayed? (Current malfunction)

    Yes: 

    Check the appropriate DTC using the "Diagnostic Trouble Code (DTC)". Refer to ENGINE (DIAGNOSTICS) (H4DO (EXCEPT FOR HEV))>DIAGNOSTIC TROUBLE CODE (DTC) .

    No: 

    Go to  2.

  2. CHECK ENGINE OIL  .

    Check the engine oil amount.

    Is there a proper amount of engine oil?

    Yes: 

    Go to  3.

    No: 

    Replace engine oil. Refer to LUBRICATION (H4DO (EXCEPT FOR HEV))>ENGINE OIL>REPLACEMENT .

  3. CHECK EXHAUST SYSTEM  .

    Check exhaust system parts.

    Are there holes or loose bolts on exhaust system?

    Yes: 

    Repair the exhaust system.

    No: 

    Go to  4.

  4. CHECK AIR INTAKE SYSTEM  .

    Check the installing condition of the air intake system.

    Are there holes, loose bolts or disconnection of hose on air intake system?

    Yes: 

    Repair the air intake system.

    No: 

    Go to  5.

  5. CHECK FUEL PRESSURE  .
    WARNING: Place "NO OPEN FLAMES" signs near the working area.
    CAUTION:
    • Be careful not to spill fuel.
    • Before attaching/detaching a fuel pressure gauge, release the fuel pressure.

    Measure the fuel pressure. Refer to MECHANICAL (H4DO (EXCEPT FOR HEV))>FUEL PRESSURE>INSPECTION .

    Is the measured value 350 - 450 kPa (3.5 - 4.6 kg/cm2 , 50 - 66 psi)?

    Yes: 

    Go to  6.

    No: 

    Check the fuel pump and fuel delivery line. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>FUEL PUMP>INSPECTION . Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>FUEL DELIVERY AND EVAPORATION LINES>INSPECTION .

  6. CHECK ENGINE COOLANT TEMPERATURE SENSOR  .
    1. Start the engine and warm up completely.
    2. Using the Subaru Select Monitor or a general scan tool, read the value of [Coolant Temp.].
      NOTE:

      Is the value of [Coolant Temp.] 75°C (167°F) or more?

      Yes: 

      Go to  7.

      No: 

      Replace the engine coolant temperature sensor. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>ENGINE COOLANT TEMPERATURE SENSOR .

  7. CHECK MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR  .
    1. Start the engine and warm up engine until coolant temperature is higher than 75°C (167°F).
    2. For CVT models, set the select lever to "P" range or "N" range, and for MT models, place the shift lever in the neutral position.
    3. Turn the A/C switch to OFF.
    4. Turn all the accessory switches to OFF.
    5. Using the Subaru Select Monitor or a general scan tool, read the value of [Air Flow Rate from Mass Air Flow Sensor].
      NOTE:

      Is the value of [Air Flow Rate from Mass Air Flow Sensor] 2.0 - 5.0 g/s (0.26 - 0.66 lb/m)?

      Yes: 

      Go to  8.

      No: 

      Replace the mass air flow and intake air temperature sensor. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR .

  8. CHECK MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR  .
    1. Start the engine and warm up engine until coolant temperature is higher than 75°C (167°F).
    2. For CVT models, set the select lever to "P" range or "N" range, and for MT models, place the shift lever in the neutral position.
    3. Turn the A/C switch to OFF.
    4. Turn all the accessory switches to OFF.
    5. Open the front hood.
    6. Measure the ambient temperature.
    7. Using the Subaru Select Monitor or a general scan tool, read the value of [Intake Air Temp.].
      NOTE:

      Subtract ambient temperature from [Intake Air Temp.]. Is the obtained value -10 - 50°C (-18 - 90°F)?

      Yes: 

      Go to  9.

      No: 

      Check the mass air flow and intake air temperature sensor. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR .

  9. CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from ECM.
    3. Disconnect the connector from fuel injector on faulty cylinders.
    4. Measure the resistance between fuel injector connector and engine ground on faulty cylinders.

      Connector & terminal 

      #1 (E5) No. 1 - Engine ground:

      #1 (E5) No. 2 - Engine ground:

      #2 (E16) No. 1 - Engine ground:

      #2 (E16) No. 2 - Engine ground:

      #3 (E6) No. 1 - Engine ground:

      #3 (E6) No. 2 - Engine ground:

      #4 (E17) No. 1 - Engine ground:

      #4 (E17) No. 2 - Engine ground:

      Is the resistance 1 MΩ or more?

      Yes: 

      Go to  10.

      No: 

      Repair the short circuit to ground in harness between ECM and fuel injector connector.

  10. CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR  .

    Measure the resistance of harness between ECM and fuel injector connector on faulty cylinders.

    Connector & terminal 

    #1 (E158) No. 96 - (E5) No. 1:

    #1 (E158) No. 87 - (E5) No. 2:

    #2 (E158) No. 95 - (E16) No. 1:

    #2 (E158) No. 86 - (E16) No. 2:

    #3 (E158) No. 93 - (E6) No. 1:

    #3 (E158) No. 84 - (E6) No. 2:

    #4 (E158) No. 94 - (E17) No. 1:

    #4 (E158) No. 85 - (E17) No. 2:

    Is the resistance less than 1Ω?

    Yes: 

    Go to  11.

    No: 

    Repair the open circuit in harness between ECM and fuel injector connector.

  11. CHECK FUEL INJECTOR  .

    Check the fuel injector on faulty cylinder. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>FUEL INJECTOR>INSPECTION .

    Is the check result OK?

    Yes: 

    Go to  12.

    No: 

    Replace the faulty fuel injector. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>FUEL INJECTOR .

  12. CHECK INSTALLATION CONDITION OF CAMSHAFT POSITION SENSOR AND CRANKSHAFT POSITION SENSOR  .

    Check the installation condition of the camshaft position sensor and crankshaft position sensor.

    Is the camshaft position sensor or crankshaft position sensor loosely installed?

    Yes: 

    Tighten the camshaft position sensor or crankshaft position sensor. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>CAMSHAFT POSITION SENSOR>INSTALLATION . Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>CRANKSHAFT POSITION SENSOR>INSTALLATION .

    No: 

    Go to  13.

  13. CHECK CRANKSHAFT POSITION SENSOR PLATE  .

    Check the crankshaft position sensor plate.

    Is the crankshaft position sensor plate rusted or does it have broken teeth?

    Yes: 

    Replace the crankshaft position sensor plate. Refer to MECHANICAL (H4DO (EXCEPT FOR HEV))>CYLINDER BLOCK .

    No: 

    Go to  14.

  14. CHECK INSTALLATION CONDITION OF TIMING CHAIN  .

    Turn the crankshaft using ST, and align the alignment mark on crank sprocket with alignment mark on cylinder block.

    ST 18252AA000 CRANKSHAFT SOCKET 

    Is the timing chain dislocated from its proper position?

    Yes: 

    Correct the installation condition of timing chain. Refer to MECHANICAL (H4DO (EXCEPT FOR HEV))>TIMING CHAIN ASSEMBLY .

    No: 

    Go to  15.

  15. CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from ECM.
    3. Disconnect the connectors from electronic throttle control.
    4. Measure the resistance between ECM connector and chassis ground.

      Connector & terminal 

      (E158) No. 27 - Chassis ground:

      (E158) No. 29 - Chassis ground:

      (E158) No. 29 - (E158) No. 44:

      (E158) No. 43 - Chassis ground:

      (E158) No. 43 - (E158) No. 44:

      Is the resistance 1 MΩ or more?

      Yes: 

      Go to  16.

      No: 

      Repair the ground short circuit of harness between ECM connector and electronic throttle control connector.

  16. CHECK SHORT CIRCUIT INSIDE THE ECM  .
    1. Connect the connector to ECM.
    2. Measure the resistance between electronic throttle control connector and engine ground.

      Connector & terminal 

      (E57) No. 6 - Engine ground:

      (E57) No. 4 - Engine ground:

      Is the resistance 1 MΩ or more?

      Yes: 

      Go to  17.

      No: 

      Repair the ground short circuit of harness between ECM connector and electronic throttle control connector. Replace the ECM if defective. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>ENGINE CONTROL MODULE (ECM) .

  17. CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL (OPEN)  .
    1. Disconnect the connector from ECM.
    2. Measure the resistance of harness between ECM connector and electronic throttle control connector.

      Connector & terminal 

      (E158) No. 29 - (E57) No. 6:

      (E158) No. 43 - (E57) No. 4:

      (E158) No. 30 - (E57) No. 3:

      Is the resistance less than 1Ω?

      Yes: 

      Go to  18.

      No: 

      Repair the harness and connector.

      NOTE: In this case, repair the following item:
      • Open circuit in harness between ECM connector and electronic throttle control connector
      • Poor contact of coupling connector
  18. CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL (OPEN)  .
    1. Connect the connector to ECM.
    2. Measure the resistance between electronic throttle control connector and engine ground.

      Connector & terminal 

      (E57) No. 3 - Engine ground:

      Is the resistance less than 5Ω?

      Yes: 

      Go to  19.

      No: 

      Repair the harness and connector.

      NOTE: In this case, repair the following item:
      • Open circuit of harness between ECM connector and engine ground
      • Poor contact of ECM connector
  19. CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL (SHORT TO POWER SUPPLY)  .
    1. Turn the ignition switch to ON.
    2. Measure the voltage between electronic throttle control connector and engine ground.

      Connector & terminal 

      (E57) No. 6 (+) - Engine ground (-):

      (E57) No. 4 (+) - Engine ground (-):

      Is the voltage 5 V or more?

      Yes: 

      Repair the short circuit to power in the harness between ECM connector and electronic throttle control connector.

      No: 

      Go to  20.

  20. CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL (SHORT BETWEEN LINES)  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from ECM.
    3. Measure the resistance between ECM connectors.

      Connector & terminal 

      (E158) No. 27 - (E158) No. 29:

      (E158) No. 27 - (E158) No. 43:

      Is the resistance 1 MΩ or more?

      Yes: 

      Go to  21.

      No: 

      Repair the short circuit between lines in harness between ECM connector and electronic throttle control connector.

  21. CHECK SENSOR OUTPUT  .
    1. Connect all connectors.
    2. Turn the ignition switch to ON.
    3. Using the Subaru Select Monitor, read the value in [Main-Throttle Sensor].
      NOTE: For detailed operation procedures, refer to "Data Monitor". Refer to ENGINE (DIAGNOSTICS (H4DO (EXCEPT FOR HEV))>DATA MONITOR .

      Is the value of [Main-Throttle Sensor] 0.81 - 0.87 V?

      Yes: 

      Go to  22.

      No: 

      Repair the poor contact of electronic throttle control connector. Replace the electronic throttle control if defective. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>THROTTLE BODY .

  22. CHECK SENSOR OUTPUT  .

    Using the Subaru Select Monitor, read the value in [Sub-Throttle Sensor].

    NOTE: For detailed operation procedures, refer to "Data Monitor". Refer to ENGINE (DIAGNOSTICS) (H4DO (EXCEPT FOR HEV))>DATA MONITOR .

    Is the value of [Sub-Throttle Sensor] 1.64 - 1.70 V?

    Yes: 

    Go to  23.

    No: 

    Repair the poor contact of electronic throttle control connector. Replace the electronic throttle control if defective. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>THROTTLE BODY .

  23. CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from ECM.
    3. Disconnect the connectors from electronic throttle control.
    4. Measure the resistance between ECM connector and electronic throttle control connector.

      Connector & terminal 

      (E158) No. 29 - (E57) No. 6:

      (E158) No. 43 - (E57) No. 4:

      (E158) No. 30 - (E57) No. 3:

      Is the resistance less than 1Ω?

      Yes: 

      Go to  24.

      No: 

      Repair the open circuit of harness between ECM connector and electronic throttle control connector.

  24. CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL (SHORT TO POWER SUPPLY)  .
    1. Connect the connector to ECM.
    2. Turn the ignition switch to ON.
    3. Measure the voltage between electronic throttle control connector and engine ground.

      Connector & terminal 

      (E57) No. 2 (+) - Engine ground (-):

      (E57) No. 1 (+) - Engine ground (-):

      Is the voltage 5 V or more?

      Yes: 

      Repair the short circuit to power in the harness between ECM connector and electronic throttle control connector.

      No: 

      Go to  25.

  25. CHECK HARNESS BETWEEN ECM AND ELECTRONIC THROTTLE CONTROL (SHORT TO GROUND)  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from ECM.
    3. Measure the resistance between electronic throttle control connector and engine ground.

      Connector & terminal 

      (E57) No. 2 - Engine ground:

      (E57) No. 1 - Engine ground:

      Is the resistance 1 MΩ or more?

      Yes: 

      Go to  26.

      No: 

      Repair the ground short circuit of harness between ECM connector and electronic throttle control connector.

  26. CHECK HARNESS BETWEEN ELECTRONIC THROTTLE CONTROL CONNECTOR (SHORT BETWEEN LINES)  .

    Measure the resistance between electronic throttle control connectors.

    Connector & terminal 

    (E57) No. 2 - (E57) No. 1:

    Is the resistance 1 MΩ or more?

    Yes: 

    Go to  27.

    No: 

    Repair the short circuit in harness between ECM connector and electronic throttle control connector.

  27. CHECK ELECTRONIC THROTTLE CONTROL GROUND CIRCUIT (OPEN)  .

    Measure the resistance between ECM connector and chassis ground.

    Connector & terminal 

    (B134) No. 69 - Chassis ground:

    (B134) No. 70 - Chassis ground:

    (B134) No. 71 - Chassis ground:

    (B134) No. 72 - Chassis ground:

    Is the resistance less than 5Ω?

    Yes: 

    Go to  28.

    No: 

    Repair the open circuit in harness between ECM connector and engine ground.

  28. CHECK ELECTRONIC THROTTLE CONTROL  .

    Measure the resistance between electronic throttle control terminals.

    Terminals 

    No. 2 - No. 1:

    Is the resistance 50Ω or less?

    Yes: 

    Go to  29.

    No: 

    Replace the electronic throttle control. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>THROTTLE BODY .

  29. CHECK ELECTRONIC THROTTLE CONTROL  .

    Move the throttle valve to the fully opened and fully closed positions with fingers.

    Check that the valve returns to the specified position when releasing fingers.

    Does the valve return to the specified position? Standard value: 3 mm (0.12 in) from fully closed position

    Repair the poor contact of ECM connector.

    Replace the electronic throttle control. Refer to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>THROTTLE BODY .

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