1
CHECK FOR 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 (A/F) OXYGEN SENSOR DATA.
- Start engine.
- While observing the Subaru Select Monitor or OBD-II general scan tool screen, warm-up the engine until coolant temperature is above 75°C (167°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 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 0.86 -1.15 at idle? |
Go to step 3. |
Go to step 4. |
3
CHECK REAR OXYGEN SENSOR SIGNAL.
- Race engine at speeds from idling to 5,000 rpm for a total of 5 cycles.
NOTE:
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.
- 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 O2 Rich Signal} blink? |
Check front oxygen (A/F) sensor circuit. |
Check rear oxygen sensor circuit. < Ref. to
REAR OXYGEN SENSOR
. > |
4
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 faulty parts. |
Go to step 5. |
5
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 6. |
6
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.
|
Is the measured value 284 - 314 kPa (2.9 - 3.2 kg/cm2
, 41 - 46 psi)? |
Go to step 7. |
Repair the following items.
Fuel pressure too high:
- Clogged fuel line or bent hose
Fuel pressure too low:
- Improper fuel pump discharge
- Clogged fuel supply line
|
7
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 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 8. |
Repair the following items.
Fuel pressure too high:
- Faulty pressure regulator
- Clogged fuel line or bent hose
Fuel pressure too low:
- Faulty pressure regulator
- Improper fuel pump discharge
- Clogged fuel supply line
|
8
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 9. |
Replace the engine coolant temperature sensor. < Ref. to
ENGINE COOLANT TEMPERATURE SENSOR
. > |
9
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 10
. |
Replace the mass air flow and intake air temperature sensor. < Ref. to
MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR
. > |
10
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 to 50°C (14 to 122°F)? |
Go to step 11. |
Check the mass air flow and intake air temperature sensor. < Ref. to
MASS AIR FLOW AND INTAKE AIR TEMPERATURE SENSOR
. > |
11
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. 26 - Chassis ground:
(B134) No. 33 - Chassis ground:
|
Is the resistance more than 1 M? |
Go to step 12. |
Repair ground short circuit in harness between ECM and front oxygen (A/F) sensor connector. |
12
CHECK HARNESS BETWEEN ECM AND FRONT OXYGEN (A/F) SENSOR CONNECTOR.
- Turn the ignition switch to OFF.
- Disconnect the connectors from front oxygen (A/F) sensor.
- Measure the voltage of harness between ECM connector and chassis ground.
Connector & terminal
(B134) No. 26 (+) - Chassis ground (-):
(B134) No. 33 (+) - Chassis ground (-):
|
Is the voltage more than 8 V? |
Go to step 13. |
Repair battery short circuit in harness between ECM and front oxygen (A/F) sensor connector. |
13
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. 26 - (B18) No. 4:
(B134) No. 33 - (B18) No. 3:
|
Is the resistance less than 1 ? |
Replace the front oxygen (A/F) sensor. < Ref. to
FRONT OXYGEN (A/F) SENSOR
. > |
Repair open circuit in harness between ECM and front oxygen (A/F) sensor connector. |