SUBARU LEGACY 1996 Service Repair Manual

OBD0277
W: DTC P0301
—CYLINDER 1 MISFIRE DETECTED
(MIS
—1)—
OBD0278
X: DTC P0302
—CYLINDER 2 MISFIRE DETECTED
(MIS
—2)—
OBD0279
Y: DTC P0303
—CYLINDER 3 MISFIRE DETECTED
(MIS
—3)—
OBD0280
Z: DTC P0304
—CYLINDER 4 MISFIRE DETECTED
(MIS
—4)—
DTC DETECTING CONDITION:

Two consecutive trips with fault

Immediately at fault recognition (A misfire which could
damage catalyst occurs.)
TROUBLE SYMPTOM:

Engine stalls.

Erroneous idling

Rough driving
203
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

10Z1Check DTC P0100, P0101, P0115, P0125,
P0201, P0202, P0203 and P0204 on display.
10Z2Connect Subaru Select Monitor and read data.
10Z3Check air intake system.
10Z4Check misfire symptom.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

WIRING DIAGRAM:

LHD Model
B2M0558



204
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:

RHD Model
B2M0791
10Z1CHECK DTC P0100, P0101, P0115, P0125,
P0201, P0202, P0203, AND P0204 ON
DISPLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0100,
P0101, P0115, P0125, P0201, P0202, P0203
and P0204?
: Inspect DTC P0100, P0101, P0115, P0125,
P0201, P0202, P0203 and P0204 using“10. Diag-
nostics Chart with Trouble Code 2-7 [T1000]”.
NOTE:
In this case, it is not necessary to inspect DTC P0301,
P0302, P0303 and P0304.
: Go to step10Z2.
205
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

OBD0145A
10Z2CONNECT SUBARU SELECT MONITOR
AND READ DATA.
1) Turn ignition switch to OFF.
2) Connect Subaru Select Monitor to the data link connec-
tor.
3) Turn ignition switch to ON and turn Subaru Select Moni-
tor switch to ON.
B2M0759
4) Read data on Subaru Select Monitor.
Designate mode use function key.
Function mode: F42
NOTE:
F42: Maximum and minimum EGR system pressure value
are indicated at the same time.
5) Print out the displayed data on paper.
G3M0152
6) Clear memory on Subaru Select Monitor.
Designate mode use function key.
Press [F], [C], [0], [ENT] in that order.
OBD0008C
7) Start engine, and drive the vehicle more than 10 min-
utes.
: Is the MIL coming on or blinking?
: Go to step10Z3.
: Go to next.
206
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

: Has the vehicle been run empty of fuel?
: Finish diagnostics operation, if the engine has no
abnormality.
: Go to next.
: Was the cause of misfire diagnosed when
the engine is running?
NOTE:
Ex. Remove spark plug cord, etc.
: Finish diagnostics operation, if the engine has no
abnormality.
: Repair connector.
NOTE:
In this case, repair the following:

Poor contact in ignitor connector

Poor contact in ignition coil connector

Poor contact in fuel injector connector on faulty cylinders

Poor contact in ECM connector

Poor contact in coupling connector (B22)
10Z3
CHECK AIR INTAKE SYSTEM.
: Is there a fault in air intake system?
NOTE:
Check the following items:

Are there air leaks or air suction caused by loose or dis-
located nuts and bolts?

Are there cracks or any disconnection of hoses?
: Repair air intake system.
: Go to step10Z4.
OBD0145A
10Z4
CHECK MISFIRE SYMPTOM.
1) Turn ignition switch to OFF.
2) Connect the Subaru Select Monitor or the OBD-II gen-
eral scan tool to data link connector.
3) Turn ignition switch to ON, and turn Subaru Select
Monitor or OBD-II general scan tool switch to ON.
207
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

G3M0152
4) Read diagnostic trouble code (DTC).

Subaru Select Monitor
Designate mode use function key.
Function mode: FB1

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Operation Manual.
NOTE:
Perform diagnosis according to the items listed below.
DTC Next action
Only one cylinder Go to step
1.
P0301 and P0302 Go to step
2.
P0303 and P0304 Go to step
3.
P0301 and P0303 Go to step
4.
P0302 and P0304 Go to step
5.
Others Go to step
6.
1ONLY ONE CYLINDER
: Is there a fault in that cylinder?
NOTE:
Check the following items.

Spark plug

Spark plug cord

Fuel injector

Compression ratio
: Go to next.
: Go to DTC P0170, 2-7 [T10P3], [T10P4] and
[T10P5].

2GROUP OF #1 AND #2 CYLINDERS
: Are there faults in #1 and #2 cylinders?
NOTE:
Check the following items.

Spark plugs

Fuel injectors

Ignition coil
: Go to next.
: Go to DTC P0170, 2-7 [T10P3], [T10P4] and
[T10P5].
NOTE:
If no abnormal is discovered, check for“8. F: IGNITION
SYSTEM”of #1 and #2 cylinders side.
208
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

3GROUP OF #3 AND #4 CYLINDERS
: Are there faults in #3 and #4 cylinders?
NOTE:
Check the following items.

Spark plugs

Fuel injectors

Ignition coil
: Go to next.
: Go to DTC P0170, 2-7 [T10P3], [T10P4] and
[T10P5].
NOTE:
If no abnormal is discovered, check for“8. F: IGNITION
SYSTEM”of #3 and #4 cylinders side.

4GROUP OF #1 AND #3 CYLINDERS
: Are there faults in #1 and #3 cylinders?
NOTE:
Check the following items.

Spark plugs

Fuel injectors

Skipping timing belt teeth
: Go to next.
: Go to DTC P0170, 2-7 [T10P3], [T10P4] and
[T10P5].

5GROUP OF #2 AND #4 CYLINDERS
: Are there faults in #2 and #4 cylinders?
NOTE:
Check the following items.

Spark plugs

Fuel injectors

Skipping timing belt teeth
: Go to next.
: Go to DTC P0170, 2-7 [T10P3], [T10P4] and
[T10P5].

6THE CYLINDER AT RANDOM
: Is the engine idle rough?
: Go to next.
: Go to DTC P0170, 2-7 [T10P3], [T10P4] and
[T10P5].
209
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

B2M0759
: Is the minimum EGR system pressure value
(value of function mode (F42) less than 1
kPa?
NOTE:
Use the value read in step10Z2for function mode F42.
: Clean EGR valve.
CAUTION:
Do not use solvent when cleaning EGR valve
assembly, as it can damage diaphragm.
NOTE:

Remove and blow away the exhaust deposits. Make
sure the valve operates smoothly and the valve seat area
is completely cleaned.

Replace EGR valve as required.
: Go to DTC P0170, 2-7 [T10P3], [T10P4] and
[T10P5].
210
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

OBD0283
AA: DTC P0325
—KNOCK SENSOR CIRCUIT MALFUNCTION
(KNOCK)—
DTC DETECTING CONDITION:

Immediately at fault recognition
TROUBLE SYMPTOM:

Poor driving performance

Knocking occurs.
10AA1Check harness between knock sensor and
ECM connector.


10AA2Check knock sensor.
10AA3Check knock sensor.
10AA4Check input signal for ECM.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.


211
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:
B2M0559
212
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code