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:
- Detected when a malfunction occurs in two consecutive driving cycles.
CAUTION: After repair or replacement of malfunctioning parts, conduct Clear Memory Mode < Ref. to OPERATION , CLEAR MEMORY MODE > and INSPECTION MODE < Ref. to OPERATION , INSPECTION MODE. >
WIRING DIAGRAM:

Fig 1: Post Catalyst Fuel Trim System Wiring Diagram
Courtesy of SUBARU OF AMERICA, INC.

DIAGNOSTIC PROCEDURE

Step	Check	Yes	No
1 CHECK ANY OTHER DTC ON DISPLAY.	Is any other DTC displayed?	Inspect the relevant DTC using "List of Diagnostic Trouble Code (DTC)". < Ref. to LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . >	Go to step 2.
2 CHECK FRONT OXYGEN (A/F) SENSOR DATA. Start engine. While observing the Subaru Select Monitor or general scan tool screen, warm-up the engine until coolant temperature is above 70°C (158°F). If the engine is already warmed-up, operate at idle speed for at least 1 minute. Read data of front oxygen (A/F) sensor signal using Subaru Select Monitor or general scan tool. NOTE: Subaru Select Monitor For detailed operation procedure, refer to the "READ CURRENT DATA FOR ENGINE". < Ref. to SUBARU SELECT MONITOR . > General scan tool For detailed operation procedures, refer to the General Scan Tool Instruction Manual.	Is the measured value within 0.85 to 1.15?	Go to step 3.	Go to step 4.
3 CHECK FRONT OXYGEN (A/F) SENSOR DATA. Race engine at speeds from idling to 5,000 rpm for a total of 5 cycles. NOTE: Normally, A/F mixture ratio is rich with racing engine. To increase engine speed to 5,000 rpm, slowly depress accelerator pedal, taking approximately 5 seconds, and quickly release accelerator pedal to decrease engine speed.	Is the measured value more than 1.1 V?	Go to step 4.	Go to step 5.
4 CHECK REAR OXYGEN SENSOR SIGNAL. Race the engine at speeds from idling to 5,000 rpm for a total of 5 cycles. NOTE: To increase the engine speed to 5,000 rpm, slowly depress accelerator pedal, taking approx. 5 seconds, and quickly release accelerator pedal to decrease engine speed. Operate the LED operation mode for engine. NOTE: Subaru Select Monitor For detailed operation procedure, refer to the "LED OPERATION MODE FOR ENGINE". < Ref. to SUBARU SELECT MONITOR . >	Does the LED of (Rear 02 Rich Signal) blink?	Repair the poor contact in front oxygen (A/F) sensor and rear oxygen sensor connector.	Go to step 17 .
5 CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR. Turn ignition switch to OFF. Disconnect connector from ECM and front oxygen (A/F) sensor connector. Measure resistance between ECM and front oxygen (A/F) sensor. Connector & terminals (B136) No. 13 - (B18) No. 1: (B136) No. 22 - (B18) No. 2:	Is the measured value less than 5 Ω?	Go to step 6.	Repair open circuit between ECM and front oxygen (A/F) sensor.
6 CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR. Measure resistance between ECM and chassis ground. Connector & terminals (B136) No. 13 - Chassis ground: (B136) No. 22 - Chassis ground:	Is the measured value more than 1 MΩ?	Go to step 7.	Repair ground short circuit between ECM and front oxygen (A/F) sensor.
7 CHECK EXHAUST SYSTEM. Check exhaust system parts. NOTE: Check the following items. Loose installation of portions Damage (crack, hole etc.) of parts Looseness of front oxygen (A/F) sensor Looseness and ill fitting of parts between front oxygen (A/F) sensor and rear oxygen sensor	Is there any fault in exhaust system?	Repair or replace malfunctioning parts.	Go to step 8.
8 CHECK EGR VALVE.	Is EGR valve clogged?	Replace EGR valve.	Go to step 9.
9 CHECK AIR INTAKE SYSTEM.	Are there holes, loose bolts or disconnection of hose on air intake system?	Repair air intake system.	Go to step 10 .
10 CHECK PURGE CONTROL SOLENOID VALVE.	Is purge control solenoid valve clogged?	Replace purge control solenoid valve.	Go to step 11 .
11 CHECK PCV VALVE.	Is PCV valve clogged?	Replace PCV valve.	Go to step 12 .
12 CHECK FUEL PRESSURE. WARNING: Place "NO FIRE" signs near the working area. Be careful not to spill fuel on the floor. Release fuel pressure. Disconnect connector from fuel pump relay. Start the engine and run it until it stalls. After the engine stalls, crank it for five more seconds. Turn ignition switch to OFF. Connect connector to fuel pump relay. Disconnect fuel delivery hose from fuel filter, and connect fuel pressure gauge. Install fuel filler cap. Start the engine and idle while gear position is neutral. Measure fuel pressure while disconnecting pressure regulator vacuum hose from intake manifold. WARNING: Before removing fuel pressure gauge, release fuel pressure. NOTE: If fuel pressure does not increase, squeeze fuel return hose 2 to 3 times, then measure fuel pressure again.	Is the measured value within 284 to 314 kPa (2.9 to 3.2 kg/cm² , 41 to 46 psi)?	Go to step 13 .	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
13 CHECK FUEL PRESSURE. After connecting pressure regulator vacuum hose, measure fuel pressure. WARNING: Before removing fuel pressure gauge, release fuel pressure. NOTE: If 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 pressure regulator and pressure regulator vacuum hose.	Is the measured value within 206 to 235 kPa (2.1 to 2.4 kg/cm² , 30 to 34 psi)?	Go to step 14 .	Repair the following items. Fuel pressure too high Malfunctioning pressure regulator Clogged fuel return line or bent hose Fuel pressure too low Malfunctioning pressure regulator Improper fuel pump discharge Clogged fuel supply line
14 CHECK ENGINE COOLANT TEMPERATURE SENSOR. Start the engine and warm-up completely. Read 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 the "READ CURRENT DATA FOR ENGINE". < Ref. to SUBARU SELECT MONITOR . > General scan tool For detailed operation procedures, refer to the General Scan Tool Instruction Manual.	Is the measured value within 70 to 100°C (158 to 212°F)?	Go to step 15 .	Replace engine coolant temperature sensor. < Ref. to ENGINE COOLANT TEMPERATURE SENSOR . >
15 CHECK INTAKE MANIFOLD PRESSURE SENSOR SIGNAL. Start the engine and warm-up engine until coolant temperature is greater than 60°C (140°F). Place the selector lever in "N" or "P" position. Turn A/C switch to OFF. Turn all accessory switches to OFF. Read data of intake manifold pressure sensor signal using Subaru Select Monitor or general scan tool. NOTE: Subaru Select Monitor For detailed operation procedure, refer to the "READ CURRENT DATA FOR ENGINE". < Ref. to SUBARU SELECT MONITOR . > General scan tool For detailed operation procedures, refer to the General Scan Tool Instruction Manual.	Is the measured value within 24.0 to 41.3 kPa (180 to 310 mmHg, 7.09 to 12.20 inHg) when idling or within 73.3 to 106.6 kPa (550 to 800 mmHg, 21.65 to 31.50 inHg) when turning ignition switch ON?	Go to step 16 .	Replace intake air temperature and pressure sensor. < Ref. to PRESSURE SENSOR . >
16 CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR. Turn ignition switch to OFF. Disconnect connectors from ECM and front oxygen (A/F) sensor connector. Measure resistance of harness between ECM and front oxygen (A/F) sensor connector. Connector & terminal (B136) No. 13 - Chassis ground: (B136) No. 22 - Chassis ground:	Is the measured value more than 1 MΩ?	Replace front oxygen (A/F) sensor. < Ref. to FRONT OXYGEN (A/F) SENSORS	Repair short circuit between ECM and front oxygen (A/F) sensor connector.
17 CHECK HARNESS BETWEEN ECM AND REAR OXYGEN SENSOR CONNECTOR. Turn ignition switch to OFF. Disconnect connectors from ECM and rear oxygen sensor. Measure resistance of harness between ECM and rear oxygen sensor connector. Connector & terminal (B135) No. 14 - (T6) No. 4: (B135) No. 19 - (T6) No. 3:	Is the measured value more than 3 Ω?	Repair open circuit in harness between ECM and rear oxygen sensor connector.	Go to step 18 .
18 CHECK HARNESS BETWEEN REAR OXYGEN SENSOR AND ECM CONNECTOR. Turn ignition switch to OFF. Disconnect connector from rear oxygen sensor. Turn ignition switch to ON. Measure voltage between rear oxygen sensor harness connector and engine ground or chassis ground. Connector & terminal (T6) No. 4 (+) - Engine ground (-):	Is the measured value within 0.2 to 0.5 V?	Replace rear oxygen sensor. < Ref. to REAR OXYGEN SENSOR . >	Repair harness and connector. NOTE: In this case, repair the following: Open circuit in harness between rear oxygen sensor and ECM connector Poor contact in rear oxygen sensor connector Poor contact in ECM connector