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Home >> Subaru >> 2006 >> Legacy GT spec.B >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 11 (Engine Controls - Engine (Diagnostics) (H4SO)) >> Diagnostic Procedure with Diagnostic Trouble Code (DTC) >> DTC P2097 Post Catalyst Fuel Trim System Too Rich Bank 1

DTC P2097 Post Catalyst Fuel Trim System Too Rich Bank 1

WARNING: This page is about a different variant/trim than selected.

DTC DETECTING CONDITION: 

CAUTION: After repairing or replacing the defective part, perform the Clear Memory Mode < Ref. to OPERATION , Clear Memory Mode. > and Inspection Mode < Ref. to PROCEDURE , Inspection Mode. >.

WIRING DIAGRAM: 

Fig 1: Post Catalyst Fuel Trim System Too Rich Bank 1 - Wiring Diagram
G05017584
DIAGNOSIS PROCEDURE

Step Check Yes No
1 CHECK ANY OTHER DTC ON DISPLAY.  Is any other DTC displayed? Check DTC using "List of Diagnostic Trouble Code (DTC)". < Ref. to LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . >
NOTE: In this case, it is not necessary to inspect DTC P2096.
 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 connector from ECM and front oxygen (A/F) sensor connector.
  3. Measure the resistance of harness between ECM and front oxygen (A/F) sensor connector.

    Connector & terminal 

    (B135) No. 8 - (E22) No. 3: 

    (B135) No. 9 - (E22) No. 1: 

 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 in front oxygen (A/F) sensor connector
  • Poor contact in ECM connector
3 CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR. 
Measure the resistance of harness between ECM connector and chassis ground.
Connector & terminal 
(B135) No. 8 - Chassis ground: 
(B135) No. 9 - Chassis ground: 		 Is the resistance more than 1 MΩ? Repair the ground short circuit of harness between ECM and front oxygen (A/F) sensor connector. Go to step 4  .
4 CHECK OUTPUT SIGNAL FOR ECM. 
  1. Connect the connector to ECM.
  2. Turn the ignition switch to ON.
  3. Measure the voltage between ECM connector and chassis ground.

    Connector & terminal 

    (B135) No. 8 (+) - Chassis ground (-): 

 Is the voltage more than 4.5 V? Go to step 5.  Go to step 6  .
5 CHECK OUTPUT SIGNAL FOR ECM. 
Measure the voltage between ECM connector and chassis ground.
Connector & terminal 
(B135) No. 8 (+) - Chassis ground (-): 		 Is the voltage more than 10 V? Repair the battery short circuit of harness between ECM and front oxygen (A/F) sensor connector. After repair, replace the ECM. < Ref. to ENGINE CONTROL MODULE (ECM) . > Repair the poor contact of ECM connector.
6 CHECK OUTPUT SIGNAL FOR ECM. 
Measure the voltage between ECM connector and chassis ground.
Connector & terminal 
(B135) No. 9 (+) - Chassis ground (-): 		 Is the voltage more than 4.95 V? Go to step 7.  Go to step 8  .
7 CHECK OUTPUT SIGNAL FOR ECM. 
Measure the voltage between ECM connector and chassis ground.
Connector & terminal 
(B135) No. 9 (+) - Chassis ground (-): 		 Is the voltage more than 10 V? Repair the battery short circuit of harness between ECM and front oxygen (A/F) sensor connector. After repair, replace the ECM. < Ref. to ENGINE CONTROL MODULE (ECM) . > Repair the poor contact of ECM connector.
8 CHECK EXHAUST SYSTEM.  Are there holes or loose bolts on exhaust system? Repair the exhaust system. Go to step 9  .
9 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 10  .
10 CHECK FUEL PRESSURE. 
WARNING:
  • Place "NO FIRE" signs near the working area.
  • Be careful not to spill fuel.

  1. Measure the fuel pressure while disconnecting pressure regulator vacuum hose from intake manifold. < Ref. to INSPECTION , Fuel Pressure. >
WARNING: 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 284 - 314 kPa (2.9 - 3.2 kgf/cm2 , 41 - 46 psi)? Go to step 11.  Repair the following item.
Fuel pressure is too high:
  • Clogged fuel return line or bent hose

Fuel pressure is too low:
  • Improper fuel pump discharge
  • Clogged fuel supply line
11 CHECK FUEL PRESSURE. 
After connecting the pressure regulator vacuum hose, measure fuel pressure. < Ref. to INSPECTION , Fuel Pressure. >
WARNING: 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 and pressure regulator vacuum hose.
 Is the measured value 206 - 235 kPa (2.1 -2.4 kgf/cm2 , 30 - 34 psi)? Go to step 12.  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
12 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 procedure, refer to "READ CURRENT DATA FOR ENGINE". < Ref. to SUBARU SELECT MONITOR . >

  • General scan tool

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

 Is the temperature above 60°C (140°F)? Go to step 13.  Replace the engine coolant temperature sensor. < Ref. to ENGINE COOLANT TEMPERATURE SENSOR . >
13 CHECK MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR. 
  1. Start the engine and warm-up engine until coolant temperature is greater than 60°C (140°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 mass air flow and intake air temperature sensor signal using Subaru Select Monitor or general scan tool.
NOTE:
  • Subaru Select Monitor

    For detailed operation procedure, refer to "READ CURRENT DATA FOR ENGINE". < Ref. to SUBARU SELECT MONITOR . >

  • General scan tool

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

 Is the measured value 2.1 - 3.4 g/s (0.28 - 0.45 lb/m)? Go to step 14.  Replace the mass air flow and intake air temperature sensor. < Ref. to MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR . >
14 CHECK MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR. 
  1. Start the engine and warm-up engine until coolant temperature is greater than 60°C (140°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 mass air flow and intake air temperature sensor signal using Subaru Select Monitor or general scan tool.
NOTE:
  • Subaru Select Monitor

    For detailed operation procedure, refer to "READ CURRENT DATA FOR ENGINE". < Ref. to SUBARU SELECT MONITOR . >

  • General scan tool

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

 Subtract ambient temperature from intake air temperature. Is the obtained value -10 - 50°C (14-122°F)? Go to step 15.  Check the mass air flow and intake air temperature sensor. < Ref. to MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR . >
15 CHECK REAR OXYGEN SENSOR DATA. 
  1. Warm-up the engine until engine coolant temperature is above 70°C (158°F), and keep the engine speed at 5,000 rpm.
  2. Read the data of rear oxygen sensor signal using Subaru Select Monitor or general scan tool.
NOTE:
  • Subaru Select Monitor

    For detailed operation procedure, refer to "READ CURRENT DATA FOR ENGINE". < Ref. to SUBARU SELECT MONITOR . >

  • General scan tool

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

 Is the voltage more than 490 mV? Go to step 18.  Go to step 16  .
16 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 

    (B135) No. 4 - (E23) No. 3: 

    (B134) NO. 29 - (E23) No. 4: 

 Is the resistance more than 3 Ω? Repair the open circuit of harness between ECM and rear oxygen sensor connector. Go to step 17  .
17 CHECK HARNESS BETWEEN REAR OXYGEN SENSOR AND ECM CONNECTOR. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from the rear oxygen sensor.
  3. Turn the ignition switch to ON.
  4. Measure the voltage between rear oxygen sensor harness connector and engine ground or chassis ground.

    Connector & terminal 

    (E23) No. 3 (+) - Engine ground (-): 

 Is the voltage 0.2 - 0.5 V? Replace the rear oxygen sensor. < Ref. to REAR OXYGEN SENSOR . > Repair the harness and connector.
NOTE: In this case, repair the following item:
  • Open circuit of harness between rear oxygen sensor and ECM connector
  • Poor contact of the rear oxygen sensor connector
  • Poor contact in ECM connector
18 CHECK REAR OXYGEN SENSOR DATA. 
  1. Warm-up the engine until engine coolant temperature is above 70°C (158°F), and rapidly reduce the engine speed from 5,000 rpm.
  2. Read the data of rear oxygen sensor signal using Subaru Select Monitor or general scan tool.
NOTE:
  • Subaru Select Monitor

    For detailed operation procedure, refer to "READ CURRENT DATA FOR ENGINE". < Ref. to SUBARU SELECT MONITOR . >

  • General scan tool

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

 Is the voltage less than 250 mV? Contact the SOA service center. Go to step 19  .
19 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 

    (B135) No. 4 - (E23) No. 3: 

    (B134) No. 29 - (E23) No. 4: 

 Is the resistance more than 3Ω? Repair the open circuit of harness between ECM and rear oxygen sensor connector. Go to step 20  .
20 CHECK HARNESS BETWEEN REAR OXYGEN SENSOR AND ECM CONNECTOR. 
  1. Turn the ignition switch to OFF.
  2. Disconnect the connector from the rear oxygen sensor.
  3. Turn the ignition switch to ON.
  4. Measure the voltage between rear oxygen sensor harness connector and engine ground or chassis ground.

    Connector & terminal 

    (E23) No. 3 (+) - Engine ground (-): 

 Is the voltage 0.2 - 0.5 V? Replace the rear oxygen sensor. < Ref. to REAR OXYGEN SENSOR . > Repair the harness and connector.
NOTE: In this case, repair the following item:
  • Open circuit of harness between rear oxygen sensor and ECM connector
  • Poor contact of the rear oxygen sensor connector
  • Poor contact in ECM connector
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