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Home >> Subaru >> 2011 >> Legacy Premium, Automatic CVT >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 16 (Engine Diagnostics (H6DO)) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P0306 Cylinder 6 Misfire Detected >> Wiring Diagram

DTC P0306 Cylinder 6 Misfire Detected: Wiring Diagram

WARNING: This page is about a different variant/trim than selected.
Fig 1: Cylinder 6 Misfire Detected Wiring Diagram
G06648024Courtesy of SUBARU OF AMERICA, INC.
Step Check Yes No
1 CHECK OUTPUT SIGNAL OF ECM. 
  1. Turn the ignition switch to ON.
  2. Measure the voltage between ECM and chassis ground on faulty cylinders.

    Connector & terminal 

    #1 (B134) No. 10 (+) - Chassis ground (-): 

    #2 (B134) No. 11 (+) - Chassis ground (-): 

    #3 (B134) No. 12 (+) - Chassis ground (-): 

    #4 (B134) No. 13 (+) - Chassis ground (-): 

    #5 (B134) No. 23 (+) - Chassis ground (-): 

    #6 (B134) No. 24 (+) - Chassis ground (-): 

 Is the voltage 10 V or more? Go to step 6.  Go to step 2  .
2 CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from fuel injector on faulty cylinders.
  3. Measure the resistance between fuel injector connector and engine ground on faulty cylinders.

    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 resistance 1 MΩ or more? Go to step 3.  Repair the short circuit to ground in harness between ECM and fuel injector connector.
3 CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR. 
Measure the resistance of harness between ECM and fuel injector connector on faulty cylinders.
Connector & terminal 
#1 (B134) No. 10 - (E5) No. 1: 
#2 (B134) No. 11 - (E16) No. 1: 
#3 (B134) No. 12 - (E6) No. 1: 
#4 (B134) No. 13 - (E17) No. 1: 
#5 (B134) No. 23 - (E43) No. 1: 
#6 (B134) No. 24 - (E44) No. 1: 		 Is the resistance less than 1 Ω? Go to step 4.  Repair the harness and connector.
NOTE: In this case, repair the following item:
  • Open circuit in harness between ECM and fuel injector connector
  • Poor contact of coupling connector
4 CHECK FUEL INJECTOR. 
Measure the resistance between fuel injector terminals on faulty cylinder.
Terminals 
No. 1 - No. 2: 		 Is the resistance 5 - 20 Ω? Go to step 5.  Replace the faulty fuel injector. Refer to FUEL INJECTOR Fuel Injector.
5 CHECK POWER SUPPLY LINE. 
  1. Turn the ignition switch to ON.
  2. Measure the voltage between fuel injector connector of faulty cylinders 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 voltage 10 V or more? Repair the poor contact of all connectors in fuel injector circuit. 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
6 CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from fuel injector on faulty cylinders.
  3. Turn the ignition switch to ON.
  4. Measure the voltage between ECM and chassis ground on faulty cylinders.

    Connector & terminal 

    #1 (B134) No. 10 (+) - Chassis ground (-): 

    #2 (B134) No. 11 (+) - Chassis ground (-): 

    #3 (B134) No. 12 (+) - Chassis ground (-): 

    #4 (B134) No. 13 (+) - Chassis ground (-): 

    #5 (B134) No. 23 (+) - Chassis ground (-): 

    #6 (B134) No. 24 (+) - Chassis ground (-): 

 Is the voltage 10 V or more? Repair the short circuit to power in harness between ECM and fuel injector connector. Go to step 7  .
7 CHECK FUEL INJECTOR. 
  1. Turn the ignition switch to OFF.
  2. Measure the resistance between fuel injector terminals on faulty cylinder.

    Terminals 

    No. 1 - No. 2: 

 Is the resistance 5 - 20 Ω? Replace the faulty fuel injector. Refer to FUEL INJECTOR Fuel Injector. Go to step 8  .
8 CHECK INSTALLATION OF CAMSHAFT POSITION SENSOR/CRANKSHAFT POSITION SENSOR.  Is the camshaft position sensor or crankshaft position sensor loosely installed? Tighten the camshaft position sensor or crankshaft position sensor. Go to step 9  .
9 CHECK CRANK PLATE.  Is the crank sprocket rusted or the teeth of crank plate broken? Replace the crank plate. Refer to CYLINDER BLOCK Cylinder Block. Go to step 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? Correct the installation condition of timing chain. Refer to TIMING CHAIN ASSEMBLY Timing Chain Assembly. Go to step 11  .
11 CHECK FUEL LEVEL.  Is the fuel meter indication lower than the "Lower" level? Refill the fuel so that the fuel meter indication is higher than the "Lower" level, and proceed to the next step. Go to step 13.  Go to step 12  .
12 CHECK STATUS OF MALFUNCTION INDICATOR LIGHT. 
  1. Clear the memory using the Subaru Select Monitor or general scan tool. Refer to , CLEAR MEMORY MODE .
  2. Start the engine, and drive the vehicle 10 minutes or more.
 Does the malfunction indicator light illuminate or blink? Go to step 14.  Go to step 13  .
13 CHECK CAUSE OF MISFIRE.  Was the cause of misfire identified when the engine is running? Finish diagnostics operation, if the engine has no abnormality. 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
14 CHECK AIR INTAKE SYSTEM.  Is there any fault in air intake system? 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?
 Go to step 15  .
15 CHECK MISFIRE SYMPTOM. 
  1. Turn the ignition switch to ON.
  2. Check for DTC. Refer to , READ DIAGNOSTIC TROUBLE CODE (DTC) .
 Does the Subaru Select Monitor or general scan tool indicate only one DTC? Go to step 21.  Go to step 16  .
16 CHECK FOR ANY OTHER DTC ON DISPLAY.  Are DTCs P0301 and P0302 displayed? Go to step 22.  Go to step 17  .
17 CHECK DTC ON DISPLAY.  Are DTCs P0303 and P0304 displayed? Go to step 23.  Go to step 18  .
18 CHECK DTC ON DISPLAY.  Is DTC P0305 and P0306 displayed? Go to step 24.  Go to step 19  .
19 CHECK DTC ON DISPLAY.  Is DTC P0301, P0303 and P0305 displayed? Go to step 25.  Go to step 20  .
20 CHECK DTC ON DISPLAY.  Is DTC P0302, P0304 and P0306 displayed? Go to step 26.  Go to step 27  .
21 ONLY ONE CYLINDER.  Is there any fault in the cylinder? Repair or replace faulty parts.
NOTE: Check the following items.
  • Spark plug
  • Fuel injector
  • Compression ratio
 Check DTC P0171, P0172, P0174 or P0175 using "List of Diagnostic Trouble Code (DTC)". Refer to , LIST OF DIAGNOSTIC TROUBLE CODE (DTC) .
22 GROUP OF #1 AND #2 CYLINDERS.  Are there any faults in #1 and #2 cylinders? Repair or replace faulty parts.
NOTE:
  • Check the following items.
    • Spark plug
    • Fuel injector
    • Ignition coil
    • Compression ratio
  • If any fault is not found, check the "IGNITION CONTROL SYSTEM" of #1 and #2 cylinders side. Refer to , IGNITION CONTROL SYSTEM , Diagnostics for Engine Starting Failure.
 Check DTC P0171, P0172, P0174 or P0175 using "List of Diagnostic Trouble Code (DTC)". Refer to , LIST OF DIAGNOSTIC TROUBLE CODE (DTC) .
23 GROUP OF #3 AND #4 CYLINDERS.  Are there any faults in #3 and #4 cylinders? Repair or replace faulty parts.
NOTE:
  • Check the following items.
    • Spark plug
    • Fuel injector
    • Ignition coil
    • Compression ratio
  • If any fault is not found, check the "IGNITION CONTROL SYSTEM" of #3 and #4 cylinders side. Refer to , IGNITION CONTROL SYSTEM , Diagnostics for Engine Starting Failure.
 Check DTC P0171, P0172, P0174 or P0175 using "List of Diagnostic Trouble Code (DTC)". Refer to , LIST OF DIAGNOSTIC TROUBLE CODE (DTC) .
24 GROUP OF #5 AND #6 CYLINDERS.  Are there any faults in #5 and #6 cylinders? Repair or replace faulty parts.
NOTE:
  • Check the following items.
    • Spark plug
    • Fuel injector
    • Ignition coil
    • Compression ratio
  • If any fault is not found, check the "IGNITION CONTROL SYSTEM" of #5 and #6 cylinders side. Refer to , IGNITION CONTROL SYSTEM , Diagnostics for Engine Starting Failure.
 Check DTC P0171, P0172, P0174 or P0175 using "List of Diagnostic Trouble Code (DTC)". Refer to , LIST OF DIAGNOSTIC TROUBLE CODE (DTC) .
25 GROUP OF #1, #3 AND #5 CYLINDERS.  Is there any fault in #1, #3 and #5 cylinders? Repair or replace faulty parts.
NOTE: Check the following items.
  • Spark plug
  • Fuel injector
  • Compression ratio
  • Skipping timing chain teeth
 Check DTC P0171, P0172, P0174 or P0175 using "List of Diagnostic Trouble Code (DTC)". Refer to , LIST OF DIAGNOSTIC TROUBLE CODE (DTC) .
26 GROUP OF #2, #4 AND #6 CYLINDERS.  Is there any fault in #2, #4 and #6 cylinders? Repair or replace faulty parts.
NOTE: Check the following items.
  • Spark plug
  • Fuel injector
  • Compression ratio
  • Skipping timing chain teeth
 Check DTC P0171, P0172, P0174 or P0175 using "List of Diagnostic Trouble Code (DTC)". Refer to , LIST OF DIAGNOSTIC TROUBLE CODE (DTC) .
27 CYLINDER AT RANDOM.  Is the engine idle rough? Check DTC P0171, P0172, P0174 or P0175 using "List of Diagnostic Trouble Code (DTC)". Refer to , LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . Repair or replace faulty parts.
NOTE: Check the following items.
  • Spark plug
  • Fuel injector
  • Compression ratio
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