Engine Controls - Tests W/codes: Other Subaru Forester SF

HARD FAILURES

Hard failures cause Malfunction Indicator Light (MIL) to illuminate and remain on until problem is repaired. If MIL comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined using Diagnostic Trouble Code (DTC) charts. If a sensor fails, control unit will use a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, vehicle runs but driveability will not be optimum.

INTERMITTENT FAILURES

Intermittent failures may cause MIL to flicker or illuminate then go out after intermittent fault goes away. However, a corresponding DTC will be retained in PCM memory. If related fault does not reoccur within a certain time frame, related DTC will be erased from PCM memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article in this section.

RETRIEVING CODES

Note. Subaru Select Monitor (SSM) or an OBD-II scan tool must be used to perform self-diagnostic tests. Follow scan tool manufacturer's instructions for proper operation. SSM can be plugged into either the OBD-II DLC or the dedicated SSM test connectors behind the dash. (Scheme 6)and (Scheme 7).

Connect scan tool to DLC located on lower left side of dash. Retrieve Diagnostic Trouble Codes (DTCs) and freeze frame data, following scan tool manufacturer's instructions. Scan tool functions consist of

1. MODE 01 - Current powertrain diagnostic data.
2. MODE 02 - Powertrain freeze frame data.
3. MODE 03 - Emission-related powertrain DTCs.
4. MODE 04 - Clear/reset emission-related diagnostic information.
5. MODE 05 - Oxygen sensor monitoring test results.

Scheme 6

Scheme 7

CLEARING CODES

Clear DTC(s) using scan tool (MODE 04). Refer to scan tool manufacturer's instruction. Disconnecting negative battery terminal will also clear DTC(s), but radio presets will be erased.

* PLEASE READ FIRST *

Note. Subaru Select Monitor (SSM) or an OBD-II scan tool must be used to perform self-diagnostic tests. Values given in tests are based on the use of SSM scan tool. Follow scan tool manufacturer's instructions.

"a" - Only One Cylinder

Check following items for that cylinder

1. Spark plug.
2. Spark plug wire.
3. Fuel injector.
4. Compression.

Repair or replace as needed. If no problems are found, go to step 6).

"b" - Group Of Cylinders No. 1 & 2

Check following items for cylinders No. 1 and 2

1. Spark plugs.
2. Fuel injectors.
3. Igniters, ignition coils, etc. Repair or replace as needed. If no problems are found, go to step 6).

"c" - Group Of Cylinders No. 3 & 4

Check following items for cylinders No. 3 and 4

1. Spark plugs.
2. Fuel injectors.
3. Igniters, ignition coils, etc.

Repair or replace as needed. If no problems are found, go to step 6).

"d" - Group Of Cylinders No. 1 & 3

Check following items for cylinders No. 1 and 3

1. Spark plugs.
2. Fuel injectors.
3. Skipped/jumped timing belt teeth.

Repair or replace as needed. If no problems are found, go to step 6).

"e" - Group Of Cylinders No. 2 & 4

Check following items for cylinders No. 2 and 4

1. Spark plugs.
2. Fuel injectors.
3. Skipped/jumped timing belt teeth.

Repair or replace as needed. If no problems are found, go to step 6).

"f" - Cylinder At Random

If engine idle is not rough, go to DTC P0170 and retest.

"a"

Connect scan tool to DLC.

"b"

Conduct CLEAR MEMORY and INSPECTION MODES.

Start and warm engine until radiator fan completes one cycle (all accessories OFF).

Turn scan tool on.

Operate the LED operation mode for engine. Select SYSTEM CHECK from Main Menu screen. Select EGI/EMPI, CURRENT DATA DISPLAY. Select DATA and LED DISPLAY.

"f"

Drive vehicle at 52-58 MPH until LED of EGR SYSTEM DIAGNOSIS comes on. Diagnosis starts in 190 seconds after starting engine and requires 4 seconds to run. Keep throttle valve opening steady. Diagnosis will be interrupted if throttle opening varies.

On scan tool, select OBD System, temporary code inspect. Confirm NO TROUBLE indication on scan tool. Diagnose any other codes separately.

SUMMARY

If no hard fault codes are present, driveability symptoms exist or intermittent codes exist, proceed to TESTS W/O CODES article in this section for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.