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Home >> Subaru >> 2019 >> Outback 3.6R Limited >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System (3.6L) (Diagnostics) (2 Of 4) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0300: Random/Multiple Cylinder Misfire Detected >> Notes
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DTC P0300: Random/Multiple Cylinder Misfire Detected: Notes

DTC detecting condition: 

CAUTION:

Wiring diagram: 

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

G12410325Courtesy of SUBARU OF AMERICA, INC.
  1. CHECK OUTPUT SIGNAL OF ECM  .
    1. Turn the ignition switch to ON.
    2. Measure the voltage between ECM and chassis ground on all cylinders.

    Connector & terminal 

    #1 (E158) No. 23 (+) - Chassis ground (-):

    #2 (E158) No. 8 (+) - Chassis ground (-):

    #3 (E158) No. 9 (+) - Chassis ground (-):

    #4 (E158) No. 22 (+) - Chassis ground (-):

    #5 (E158) No. 52 (+) - Chassis ground (-):

    #6 (E158) No. 13 (+) - Chassis ground (-):

    Is the voltage 10 V or more?

    Yes  Go to  6 .

    No  Go to  2 .

  2. CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from all fuel injectors.
    3. Measure the resistance between all fuel injector connectors and engine ground.

    Connector & terminal 

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

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

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

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

    #5 (E43) No. 2 - Engine ground:

    #6 (E44) No. 2 - Engine ground:

    Is the resistance 1 MΩ or more?

    Yes  Go to  3 .

    No  Repair the short circuit to ground in harness between ECM connector and fuel injector connector.

  3. CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR  .

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

    Connector & terminal 

    #1 (E158) No. 23 - (E5) No. 2:

    #2 (E158) No. 8 - (E16) No. 2:

    #3 (E158) No. 9 - (E6) No. 2:

    #4 (E158) No. 22 - (E17) No. 2:

    #5 (E158) No. 52 - (E43) No. 2:

    #6 (E158) No. 13 - (E44) 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 fuel injector connector.

  4. CHECK FUEL INJECTOR  .

    Check all fuel injectors. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H6DO)>FUEL INJECTOR>INSPECTION .

    Is the check result OK?

    Yes  Go to  5 .

    No  Replace the faulty fuel injector. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H6DO)>FUEL INJECTOR .

  5. CHECK POWER SUPPLY LINE  .
    1. Turn the ignition switch to ON.
    2. Measure the voltage between all fuel injector connectors and the engine ground.

    Connector & terminal 

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

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

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

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

    #5 (E43) No. 1 (+) - Engine ground (-):

    #6 (E44) No. 1 (+) - Engine ground (-):

    Is the voltage 10 V or more?

    Yes  Repair the poor contact of all connectors in fuel injector circuit.

    No  Repair the harness and connector.

    NOTE: In this case, repair the following item:
    • Open circuit in harness between the main relay and fuel injector connector on faulty cylinders
    • Poor contact of coupling connector
    • Poor contact of main relay connector
    • Blown out of fuse (M/B No. 25)
  6. CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR  .
    1. Turn the ignition switch to OFF.
    2. Disconnect the connector from all fuel injectors.
    3. Turn the ignition switch to ON.
    4. Measure the voltage between ECM and chassis ground on all cylinders.

    Connector & terminal 

    #1 (E158) No. 23 (+) - Chassis ground (-):

    #2 (E158) No. 8 (+) - Chassis ground (-):

    #3 (E158) No. 9 (+) - Chassis ground (-):

    #4 (E158) No. 22 (+) - Chassis ground (-):

    #5 (E158) No. 52 (+) - Chassis ground (-):

    #6 (E158) No. 13 (+) - Chassis ground (-):

    Is the voltage 10 V or more?

    Yes  Repair the short circuit to power in harness between ECM connector and fuel injector connectors.

    No  Go to  7 .

  7. CHECK FUEL INJECTOR  .
    1. Turn the ignition switch to OFF.
    2. Check all fuel injectors. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H6DO)>FUEL INJECTOR>INSPECTION .

    Is the check result OK?

    Yes  Go to  8 .

    No  Replace the faulty fuel injector. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H6DO)>FUEL INJECTOR .

  8. CHECK INSTALLATION OF CAMSHAFT POSITION SENSOR AND CRANKSHAFT POSITION SENSOR  .

    Check 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. Ref. to FUEL INJECTION (FUEL SYSTEMS) (H6DO)>CAMSHAFT POSITION SENSOR>INSTALLATION . Ref. to FUEL INJECTION (FUEL SYSTEMS) (H6DO)>CRANKSHAFT POSITION SENSOR>INSTALLATION .

    No  Go to  9 .

  9. CHECK CRANKSHAFT POSITION SENSOR PLATE  .

    Check the crankshaft position sensor plate.

    Is the crank sprocket rusted or the teeth of crankshaft position sensor plate broken?

    Yes  Replace the crankshaft position sensor plate. Ref. to MECHANICAL (H6DO)>CYLINDER BLOCK .

    No  Go to  10 .

  10. 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. Ref. to MECHANICAL (H6DO)>TIMING CHAIN ASSEMBLY .

    No  Go to  11 .

  11. CHECK PCV VALVE  .

    Check the PCV valve. Ref. to EMISSION CONTROL (AUX. EMISSION CONTROL DEVICES) (H6DO)>PCV VALVE>INSPECTION .

    Is the check result OK?

    Yes  Go to  12 .

    No  Replace the PCV valve. Ref. to EMISSION CONTROL (AUX. EMISSION CONTROL DEVICES) (H6DO)>PCV VALVE .

  12. CHECK PCV HOSE  .

    Check the PCV hose. Ref. to EMISSION CONTROL (AUX. EMISSION CONTROL DEVICES) (H6DO)>PCV VALVE>INSPECTION>OTHER INSPECTIONS .

    Is the check result OK?

    Yes  Go to  13 .

    No  Replace the PCV hose. Ref. to EMISSION CONTROL (AUX. EMISSION CONTROL DEVICES) (H6DO)>PCV VALVE .

  13. CHECK FUEL LEVEL  .

    Inspect the fuel level.

    Is the fuel meter indication lower than the "Lower" level?

    Yes  Refill the fuel so that the fuel meter indication is higher than the "Lower" level, and proceed to the next step. Go to  14 .

    No  Go to  14 .

  14. CHECK STATUS OF MALFUNCTION INDICATOR LIGHT  .
    1. Clear the memory using the Subaru Select Monitor or general scan tool. Ref. to ENGINE (DIAGNOSTICS) (H6DO)>CLEAR MEMORY MODE .
    2. Start the engine, and drive the vehicle for 10 minutes or more at 60 km/h (37.3 MPH) or more.

    Does the malfunction indicator light illuminate or blink?

    Yes  Go to  15 .

    No  Repair the poor contact of connector.

    NOTE: In this case, repair the following item:
    • Poor contact of ignition coil connector
    • Poor contact of fuel injector connector on faulty cylinders
    • Poor contact of ECM connector
    • Poor contact of coupling connector

    Go to  15 .

  15. CHECK AIR INTAKE SYSTEM  .

    Check the air intake system.

    Is there any fault in air intake system?

    Yes  Repair the air intake system.

    NOTE: Check the following items.
    • Are there air leaks or air suction caused by loose or dislocated nuts and bolts?
    • Are there cracks or any disconnection of hoses?

    No  Go to  16 .

  16. CHECK ALL CYLINDERS  .

    Check the following items for the cylinders.

    • Spark plug
    • Ignition coil
    • Fuel injector
    • Compression
    • Skipping timing chain teeth

    Is there a fault in any cylinder?

    Yes  Repair or replace the faulty part of the faulty cylinder.

    NOTE: Check the following items.
    • Spark plug
    • Ignition coil
    • Fuel injector
    • Compression
    • Skipping timing chain teeth

    No  Go to DTC P0171. Ref. to ENGINE (DIAGNOSTICS) (H6DO)>DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)>DTC P0171 SYSTEM TOO LEAN BANK 1 .

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