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Home >> Subaru >> 2011 >> Legacy Premium, Automatic CVT >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 7 (Engine Diagnostics (H4DOTC)) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P219A Bank 1 Air-Fuel Ratio Imbalance >> Wiring Diagram

DTC P219A Bank 1 Air-Fuel Ratio Imbalance: Wiring Diagram

WARNING: This page is about a different variant/trim than selected.
Fig 1: Bank 1 Air-Fuel Ratio Imbalance Wiring Diagram (1 Of 3)
G07910312Courtesy of SUBARU OF AMERICA, INC.
Fig 2: Bank 1 Air-Fuel Ratio Imbalance Wiring Diagram (2 Of 3)
G07910315Courtesy of SUBARU OF AMERICA, INC.
Fig 3: Bank 1 Air-Fuel Ratio Imbalance Wiring Diagram (3 Of 3)
G06647754Courtesy of SUBARU OF AMERICA, INC.
Step Check Yes No
1 CHECK FRONT OXYGEN (A/F) SENSOR CONNECTOR AND COUPLING CONNECTOR.  Has water entered the connector? Completely remove any water inside. Go to step 2  .
2 CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connectors from ECM and front oxygen (A/F) sensor.
  3. Measure the resistance of harness between ECM and front oxygen (A/F) sensor connector.

    Connector & terminal 

    (B136) No. 19 - (E24) No. 3: 

    (B136) No. 18 - (E24) No. 4: 

 Is the resistance less than 1 Ω? Go to step 3  . Repair the harness and connector.
NOTE: In this case, repair the following item:
  • Open circuit in harness between ECM and front oxygen (A/F) sensor connector
  • Poor contact of coupling connector
3 CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR. 
Measure the resistance between ECM and chassis ground.
Connector & terminal 
(B136) No. 19 - Chassis ground: 
(B136) No. 18 - Chassis ground: 		 Is the resistance 1 MΩ or more? Go to step 4  . Repair the ground short circuit of harness between ECM and front oxygen (A/F) sensor connector.
4 CHECK OUTPUT SIGNAL FOR ECM. 
  1. Connect the connector to ECM.
  2. Turn the ignition switch to ON.
  3. Measure the voltage between front oxygen (A/F) sensor connector and chassis ground.

    Connector & terminal 

    (E24) No. 3 (+) - Chassis ground (-): 

 Is the voltage 4.5 V or more? Go to step 6  . Go to step 5  .
5 CHECK OUTPUT SIGNAL FOR ECM. 
Measure the voltage between front oxygen (A/F) sensor connector and chassis ground.
Connector & terminal 
(E24) No. 4 (+) - Chassis ground (-): 		 Is the voltage 4.95 V or more? Go to step 6  . Go to step 7  .
6 CHECK OUTPUT SIGNAL FOR ECM. 
Measure the voltage between front oxygen (A/F) sensor connector and chassis ground.
Connector & terminal 
(E24) No. 3 (+) - Chassis ground (-): 
(E24) No. 4 (+) - Chassis ground (-): 		 Is the voltage 8 V or more? Repair the short circuit to power in the harness between ECM and front oxygen (A/F) sensor connector. After repair, replace the ECM. Refer to FU(H4DOTC)-58, Engine Control Module (ECM). Repair the poor contact of ECM connector.
7 CHECK EXHAUST SYSTEM.  Are there holes or loose bolts on exhaust system? Repair the exhaust system. Go to step 8  .
8 CHECK AIR INTAKE SYSTEM.  Are there holes, loose bolts or disconnection of hose on air intake system? Repair the air intake system. Go to step 9  .
9 CHECK FUEL PRESSURE. 
WARNING: Place "NO OPEN FLAMES" signs near the working area.
CAUTION: Be careful not to spill fuel.

  1. Connect the front oxygen (A/F) sensor connector.
  2. Measure the fuel pressure while disconnecting pressure regulator vacuum hose from intake manifold. Refer to ME(H4DOTC)-25, INSPECTION, Fuel Pressure.
CAUTION: Release fuel pressure before removing the fuel pressure gauge.
NOTE: If fuel pressure does not increase, squeeze the fuel return hose 2 to 3 times, then measure fuel pressure again.
 Is the measured value 328 - 358 kPa (3.3 - 3.7 kg/cm2 , 48 - 52 psi)? Go to step 10  . Repair the following item.
Fuel pressure is too high:
  • Clogged fuel line or bent hose

    Fuel pressure is too low:

  • Improper fuel pump discharge
  • Clogged fuel supply line
10 CHECK FUEL PRESSURE. 
After connecting the pressure regulator vacuum hose, measure fuel pressure. Refer to ME(H4DOTC)-25, INSPECTION, Fuel Pressure.
CAUTION: Release fuel pressure before removing the fuel pressure gauge.
NOTE:
  • If fuel pressure does not increase, squeeze fuel return hose 2 to 3 times, then measure fuel pressure again.
  • If the measured value at this step is out of specification, check or replace pressure regulator vacuum hose.
 Is the measured value 274 - 304 kPa (2.8 - 3.1 kg/cm2 , 40 - 44 psi)? Go to step 11  . Repair the following item.
Fuel pressure is too high:
  • Faulty pressure regulator
  • Clogged fuel return line or bent hose

    Fuel pressure is too low:

  • Faulty pressure regulator
  • Improper fuel pump discharge
  • Clogged fuel supply line
11 CHECK ENGINE COOLANT TEMPERATURE SENSOR. 
  1. Start the engine and warm up completely.
  2. Read the data of engine coolant temperature sensor signal using Subaru Select Monitor or general scan tool.
    NOTE:
    • Subaru Select Monitor

      For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Refer to , SUBARU SELECT MONITOR .

    • General scan tool

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

 Is the engine coolant temperature 75°C (167°F) or higher? Go to step 12  . Replace the engine coolant temperature sensor. Refer to FU(H4DOTC)-33, Engine Coolant Temperature Sensor.
12 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. Place the shift lever in neutral position.
  3. Turn the A/C switch to OFF.
  4. Turn all the accessory switches to OFF.
  5. Read the data of the mass air flow and intake air temperature sensor signal using Subaru Select Monitor or general scan tool.
    NOTE:
    • Subaru Select Monitor

      For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Refer to , SUBARU SELECT MONITOR .

    • General scan tool

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

 Is the measured value 2.0 - 5.0 g/s (0.26 - 0.66 lb/m)? Go to step 13  . Replace the mass air flow and intake air temperature sensor. Refer to FU(H4DOTC)-41, Mass Air Flow and Intake Air Temperature Sensor.
13 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. Place the shift lever in 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. Read the data of the mass air flow and intake air temperature sensor signal using Subaru Select Monitor or general scan tool.
    NOTE:
    • Subaru Select Monitor

      For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Refer to , SUBARU SELECT MONITOR .

    • General scan tool

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

 Subtract ambient temperature from intake air temperature. Is the obtained value -10 - 50°C (-18 - 90°F)? Go to step 14  . Check the mass air flow and intake air temperature sensor. Refer to FU(H4DOTC)-41, Mass Air Flow and Intake Air Temperature Sensor.
14 CHECK REAR OXYGEN SENSOR DATA. 
  1. Warm up the engine until engine coolant temperature is higher than 75°C (167°F), and keep the engine speed at 3, 000 rpm. (2 minutes maximum)
  2. Read the data of rear oxygen sensor signal using Subaru Select Monitor or general scan tool.
    NOTE:
    • Depress the clutch pedal.
    • Subaru Select Monitor

      For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Refer to , SUBARU SELECT MONITOR .

    • General scan tool

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

 Is the voltage 490 mV or more? Go to step 15  . Go to step 16  .
15 CHECK REAR OXYGEN SENSOR DATA. 
  1. Warm up the engine until engine coolant temperature is higher than 75°C (167°F), and rapidly reduce the engine speed from 3, 000 rpm.
  2. Read the data of rear oxygen sensor signal using Subaru Select Monitor or general scan tool.
    NOTE:
    • Depress the clutch pedal.
    • Subaru Select Monitor

      For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Refer to , SUBARU SELECT MONITOR .

    • General scan tool

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

 Is the voltage 250 mV or less? Go to step 17  . Go to step 16  .
16 CHECK REAR OXYGEN SENSOR CONNECTOR AND COUPLING CONNECTOR.  Has water entered the connector? Completely remove any water inside. Go to step 18  .
17 CHECK FRONT OXYGEN (A/F) SENSOR USING REAR OXYGEN SENSOR SIGNAL. 
  1. Warm up the engine until engine coolant temperature is higher than 75°C (167°F), then keep the engine idling for 5 minutes or more.
  2. Read the data of rear oxygen sensor signal using Subaru Select Monitor or general scan tool.
    NOTE:
    • Subaru Select Monitor

      For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Refer to , SUBARU SELECT MONITOR .

    • General scan tool

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

 Is a voltage of 250 mV or less maintained for 5 minutes or more? Replace the front oxygen (A/F) sensor. Refer to FU(H4DOTC)-54, Front Oxygen (A/F) Sensor. Go to step 18  .
18 CHECK HARNESS BETWEEN ECM AND REAR OXYGEN SENSOR CONNECTOR. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from ECM and rear oxygen sensor.
  3. Measure the resistance of harness between ECM and rear oxygen sensor connector.

    Connector & terminal 

    (B136) No. 20 - (E25) No. 3: 

    (B135) No. 30 - (E25) No. 4: 

 Is the resistance less than 1 Ω? Go to step 19  . Repair the harness and connector.
NOTE: In this case, repair the following item:
  • Open circuit in harness between ECM and rear oxygen sensor connector
  • Poor contact of coupling connector
19 CHECK HARNESS BETWEEN ECM AND REAR OXYGEN SENSOR CONNECTOR. 
  1. Connect the connector to ECM.
  2. Turn the ignition switch to ON.
  3. Measure the voltage between rear oxygen sensor connector and chassis ground.

    Connector & terminal 

    (E25) No. 3 (+) - Chassis ground (-): 

 Is the voltage 0.2 - 0.5 V? Replace the rear oxygen sensor. Refer to FU(H4DOTC)-56, Rear Oxygen Sensor. Go to step 20  .
20 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 (-): 

 Is the voltage 10 V or more? Go to step 25  . Go to step 21  .
21 CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR. 
  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. 2 - Engine ground: 

    #2 (E16) No. 2 - Engine ground: 

    #3 (E6) No. 2 - Engine ground: 

    #4 (E17) No. 2 - Engine ground: 

 Is the resistance 1 MΩ or more? Go to step 22  . Repair the short circuit to ground in harness between ECM and fuel injector connector.
22 CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR. 
Measure the resistance of harness between ECM and fuel injector connector on faulty cylinders.
Connector & terminal 
#1 (B134) No. 10 - (E5) No. 2: 
#2 (B134) No. 11 - (E16) No. 2: 
#3 (B134) No. 12 - (E6) No. 2: 
#4 (B134) No. 13 - (E17) No. 2: 		 Is the resistance less than 1 Ω? Go to step 23  . 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
23 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 24  . Replace the faulty fuel injector. Refer to FU(H4DOTC)-44, Fuel Injector.
24 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. 1 (+) - Engine ground (-): 

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

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

    #4 (E17) No. 1 (+) - 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
25 CHECK HARNESS BETWEEN ECM AND FUEL INJECTOR CONNECTOR. 
  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 (-): 

 Is the voltage 10 V or more? Repair the short circuit to power in harness between ECM and fuel injector connector. Go to step 26  .
26 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 FU(H4DOTC)-44, Fuel Injector. Go to step 27  .
27 CHECK INSTALLATION CONDITION 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. Refer to FU(H4DOTC)-36, Camshaft Position Sensor. Refer to FU(H4DOTC)-34, Crankshaft Position Sensor. Go to step 28  .
28 CHECK CRANK SPROCKET. 
Remove the timing belt cover. Refer to ME(H4DOTC)-45, REMOVAL, Timing Belt Cover.		 Is the crank sprocket rusted or does it have broken teeth? Replace the crank sprocket. Refer to ME(H4DOTC)-60, Crank Sprocket. Go to step 29  .
29 CHECK INSTALLATION CONDITION OF TIMING BELT. 
Turn the crankshaft using ST, and align the alignment mark on crank sprocket with alignment mark on cylinder block.
ST 499987500 CRANKSHAFT SOCKET		 Is the timing belt dislocated from its proper position? Repair the installation condition of timing belt. Refer to ME(H4DOTC)-50, Timing Belt. Go to step 30  .
30 CHECK FUEL LEVEL.  Is the fuel meter indication higher than the "Lower" level? Go to step 31  . Refill the fuel so that the fuel meter indication is higher than the "Lower" level, and proceed to the next step. Go to step 31.
31 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 33  . Go to step 32  .
32 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
33 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 34  .
34 CHECK MISFIRE SYMPTOM. 
  1. Turn the ignition switch to ON.
  2. Read DTC using the Subaru Select Monitor or a general scan tool.
    NOTE:
    • Subaru Select Monitor

      For detailed operation procedures, refer to "READ CURRENT DATA FOR ENGINE". Refer to , SUBARU SELECT MONITOR .

    • General scan tool

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

 Does the Subaru Select Monitor or general scan tool indicate only one DTC? Go to step 39  . Go to step 35  .
35 CHECK DTC.  Is DTC P0301 and P0302 displayed on the Subaru Select Monitor or general scan tool? Go to step 40  . Go to step 36  .
36 CHECK DTC.  Is DTC P0303 and P0304 displayed on the Subaru Select Monitor or general scan tool? Go to step 41  . Go to step 37  .
37 CHECK DTC.  Is DTC P0301 and P0303 displayed on the Subaru Select Monitor or general scan tool? Go to step 42  . Go to step 38  .
38 CHECK DTC.  Is DTC P0302 and P0304 displayed on the Subaru Select Monitor or general scan tool? Go to step 43  . Go to step 44  .
39 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
 Go to DTC P0171. Refer to , DTC P0171 SYSTEM TOO LEAN (BANK 1) , Diagnostic Procedure with Diagnostic Trouble Code (DTC).
40 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 are not found, check the "IGNITION CONTROL SYSTEM" of #1 and #2 cylinders side. Refer to , IGNITION CONTROL SYSTEM , Diagnostics for Engine Starting Failure.
 Go to DTC P0171. Refer to , DTC P0171 SYSTEM TOO LEAN (BANK 1) , Diagnostic Procedure with Diagnostic Trouble Code (DTC).
41 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 are not found, check the "IGNITION CONTROL SYSTEM" of #3 and #4 cylinders side. Refer to , IGNITION CONTROL SYSTEM , Diagnostics for Engine Starting Failure.
 Go to DTC P0171. Refer to , DTC P0171 SYSTEM TOO LEAN (BANK 1) , Diagnostic Procedure with Diagnostic Trouble Code (DTC).
42 GROUP OF #1 AND #3 CYLINDERS.  Are there any faults in #1 and #3 cylinders? Repair or replace faulty parts.
NOTE: Check the following items.
  • Spark plug
  • Fuel injector
  • Compression ratio
  • Skipping timing belt teeth
 Go to DTC P0171. Refer to , DTC P0171 SYSTEM TOO LEAN (BANK 1) , Diagnostic Procedure with Diagnostic Trouble Code (DTC).
43 GROUP OF #2 AND #4 CYLINDERS.  Are there any faults in #2 and #4 cylinders? Repair or replace faulty parts.
NOTE: Check the following items.
  • Spark plug
  • Fuel injector
  • Compression ratio
  • Skipping timing belt teeth
 Go to DTC P0171. Refer to , DTC P0171 SYSTEM TOO LEAN (BANK 1) , Diagnostic Procedure with Diagnostic Trouble Code (DTC).
44 CYLINDER AT RANDOM.  Is the engine idle rough? Go to DTC P0171. Refer to , DTC P0171 SYSTEM TOO LEAN (BANK 1) , Diagnostic Procedure with Diagnostic Trouble Code (DTC). Repair or replace faulty parts.
NOTE: Check the following items.
  • Spark plug
  • Fuel injector
  • Compression ratio
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