Wiring Diagram:

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

Fig 1: Wiring Diagram - DTC P2097 Post Catalyst Fuel Trim System Too Rich Bank 1

G03829084

Courtesy of SUBARU OF AMERICA, INC.

DTC P2097 DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1. CHECK FOR 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. Turn the ignition switch to OFF. Disconnect the connectors from ECM and front oxygen (A/F) sensor connector. Measure the resistance of harness between ECM and front oxygen (A/F) sensor connector. Connector & terminal (B134) No. 27 - (E47) No. 1: (B134) 34 - (E47) No. 3:	Is the measured value less than 1 Ω?	Go to step 3.	Repair the harness and connector. NOTE: In this case, repair the following: 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 (B134) No. 27- Chassis ground: (B134) No. 34 - Chassis ground:	Is the measured value more than 1 MΩ?	Repair the ground short circuit in harness between ECM and front oxygen (A/F) sensor connector.	Go to step 4.
4. CHECK OUTPUT SIGNAL FOR ECM. Connect the connector to ECM. Turn the ignition switch to ON. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B134) 27 (+) - Chassis ground (-):	Is the measured value 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 (B134) No. 27 (+) - Chassis ground (-):	Is the measured value more than 10 V?	Repair the battery short circuit in 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 in ECM connector.
6. CHECK OUTPUT SIGNAL FOR ECM. Measure the voltage between ECM connector and chassis ground. Connector & terminal (B134) No. 34 (+) - Chassis ground (-):	Is the measured value 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 (B134) No. 34 (+) - Chassis ground (-):	Is the measured value more than 10 V?	Repair the battery short circuit in 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 in 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 on the floor. Release the fuel pressure. Disconnect the connector from fuel pump relay. Start the engine and run it until it stalls. After the engine stalls, crank it for 5 more seconds. Turn the ignition switch to OFF. Connect the connector to fuel pump relay. Disconnect the fuel delivery hose from fuel filter, and connect fuel pressure gauge. Install the fuel filler cap. Start the engine and idle while gear position is neutral. Measure the fuel pressure while disconnecting pressure regulator vacuum hose from intake manifold. WARNING: Before removing the fuel pressure gauge, release fuel pressure. NOTE: If the fuel pressure does not increase, squeeze fuel return hose 2 to 3 times, then measure fuel pressure again.	Is the measured value 284 - 314 kPa (2.9 - 3.2 kg/cm² , 41 - 46 psi)?	Go to step 11.	Repair the following items. Fuel pressure too high: Clogged fuel return line or bent hose Fuel pressure too low: Improper fuel pump discharge Clogged fuel supply line
11. CHECK FUEL PRESSURE. After connecting the pressure regulator vacuum hose, measure fuel pressure. WARNING: Before removing the fuel pressure gauge, release fuel pressure. NOTE: If the fuel pressure does not increase, squeeze fuel return hose 2 to 3 times, then measure fuel pressure again. If out of specification as measured at this step, check or replace the pressure regulator and pressure regulator vacuum hose.	Is the measured value 206 - 235 kPa (2.1 - 2.4 kg/cm² , 30 - 34 psi)?	Go to step 12.	Repair the following items. Fuel pressure too high: Faulty pressure regulator Clogged fuel return line or bent hose Fuel pressure too low: Faulty pressure regulator Improper fuel pump discharge Clogged fuel supply line
12. CHECK ENGINE COOLANT TEMPERATURE SENSOR. Start the engine and warm-up completely. Read the data of engine coolant temperature sensor signal using Subaru Select Monitor or OBD-II general scan tool. NOTE: Subaru Select Monitor For detailed operation procedure, refer to the "READ CURRENT DATA FOR ENGINE". < Ref. to , SUBARU SELECT MONITOR . > OBD-II general scan tool For detailed operation procedure, refer to the OBD-II general scan tool instruction manual .	Is the temperature more than 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. Start the engine and warm-up engine until coolant temperature is greater than 60°C (140°F). Place the shift lever in neutral position. Turn the A/C switch to OFF. Turn all accessory switches to OFF. Read the data of mass air flow and intake air temperature sensor signal using Subaru Select Monitor or OBD-II general scan tool. NOTE: Subaru Select Monitor For detailed operation procedure, refer to the "READ CURRENT DATA FOR ENGINE". < Ref. to , SUBARU SELECT MONITOR . > OBD-II general scan tool For detailed operation procedure, refer to the OBD-II general scan tool instruction manual .	Is the measured value within the followings? Ignition ON: 73.3 - 106.6 kPa (550 - 800 mmHg, 21.65 -31.50 inHg) Idling: 24.0 - 41.3 kPa (180 - 310 mmHg, 7.09- 12.20 inHg)	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. Start the engine and warm-up engine until coolant temperature is greater than 60°C (140°F). Place the shift lever in neutral position. Turn the A/C switch to OFF. Turn all accessory switches to OFF. Open the front hood. Measure the ambient temperature. Read the data of mass air flow and intake air temperature sensor signal using Subaru Select Monitor or OBD-II general scan tool. NOTE: Subaru Select Monitor For detailed operation procedure, refer to the "READ CURRENT DATA FOR ENGINE". < Ref. to , SUBARU SELECT MONITOR . > OBD-II general scan tool For detailed operation procedure, refer to the OBD-II general scan tool instruction manual .	Subtract ambient temperature from intake air temperature. Is the obtained value -10°C - 50°C (14°F- 122°F)?	Contact your SOA Service Center.	Check the mass air flow and intake air temperature sensor. < Ref. to MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR . >