1997 SUBARU LEGACY check engine

OBD0240
T: DTC P0170
—FUEL TRIM MALFUNCTION—
DTC DETECTING CONDITION:

Two consecutive driving cycles with fault
TROUBLE SYMPTOM:

Erroneous idling

Engine stalls.

Poor driving performance
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODE.

10T1
CHECK EXHAUST SYSTEM.
: Are there holes or loose bolts on exhaust
system?
: Repair exhaust system.
: Go to step10T2.
10T2
CHECK AIR INTAKE SYSTEM.
: Are there holes, loose bolts or disconnec-
tion of hose on air intake system?
: Repair air intake system.
: Go to step10T3.
G2M0340
10T3
CHECK FUEL PRESSURE.
1) Release fuel pressure.
(1) Remove fuel pump access hole lid located on the
right rear of trunk compartment floor (Sedan) or lug-
gage compartment floor (Wagon).
190
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

6) After connecting pressure regulator vacuum hose, mea-
sure fuel pressure.
: Is fuel pressure between 157 and 206 kPa
(1.6—2.1 kg/cm2,23—30 psi)?
: Go to step10T4.
: 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
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.
OBD0145A
10T4CHECK ENGINE COOLANT TEMPERA-
TURE SENSOR.
DTC P0117 [T10I0].>
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) Start the engine and warm-up completely.
192
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

B2M0479
4) Read data on Subaru Select Monitor or the OBD-II gen-
eral scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F04

F04: Water temperature is indicated in“°C”and“°F”.
: Is temperature greater than 60°Cor140°Fin
function mode F04?
: Go to step10T5.
: Replace engine coolant temperature sensor.

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
OBD0145A
10T5
CHECK MASS AIR FLOW SENSOR.
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) Start the engine and warm-up engine until coolant tem-
perature is greater than 60°C (140°F).
4) Place the selector lever in“N”or“P”position.
5) Turn A/C switch to OFF.
6) Turn all accessory switches to OFF.
193
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

OBD0145A
10V1CONNECT SUBARU SELECT MONITOR
OR THE OBD-II GENERAL SCAN TOOL,
AND READ DATA.
1) Turn ignition switch to OFF.
2) Connect Subaru Select Monitor or the OBD-II general
scan tool to data link connector.
3) Turn ignition switch to ON and Subaru Select Monitor or
OBD-II general scan tool switch to ON.
4) Start engine.
H2M1308
5) Read data on Subaru Select Monitor or OBD-II general
scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F44

F44: Fuel temperature is indicated in“°C”and“°F”.
: Is the value greater than 150°Cor300°Fin
function mode F44?
: Go to step10V2.
: Even if MIL lights up, the circuit has returned to a
normal condition at this time.

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
G2M0340
10V2CHECK HARNESS BETWEEN FUEL TEM-
PERATURE SENSOR AND ECM CON-
NECTOR.
1) Turn ignition switch to OFF.
2) Remove access hole lid.
3) Disconnect connector from fuel pump.
OBD0145A
4) Connect Subaru Select Monitor or the OBD-II general
scan tool to data link connector.
5) Turn ignition switch and Subaru Select Monitor or
OBD-II general scan tool switch to ON.
198
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

OBD0145A
10W1CONNECT SUBARU SELECT MONITOR
OR THE OBD-II GENERAL SCAN TOOL,
AND READ DATA.
1) Turn ignition switch to OFF.
2) Connect Subaru Select Monitor or the OBD-II general
scan tool to data link connector.
3) Turn ignition switch to ON and Subaru Select Monitor or
OBD-II general scan tool switch to ON.
4) Start engine.
H2M1308
5) Read data on Subaru Select Monitor or OBD-II general
scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F44

F44: Fuel temperature is indicated in“°C”and“°F”.
: Is the value less than40°Cor40°Fin
function mode F44?
: Go to step10W2.
: Repair poor contact.
NOTE:
In this case, repair the following:

Poor contact in fuel pump connector

Poor contact in ECM connector

Poor contact in coupling connector (B22, B98 and R57)

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
G2M0340
10W2CHECK HARNESS BETWEEN FUEL TEM-
PERATURE SENSOR AND ECM CON-
NECTOR.
1) Turn ignition switch to OFF.
2) Remove access hole lid.
3) Disconnect connector from fuel pump.
B2M0917A
4) Measure voltage between fuel pump connector and
chassis ground.
: Connector & terminal
(R58) No. 6 (+)—Chassis ground ():
Is the voltage more than 10 V?
: Repair battery short circuit in harness between
ECM and fuel pump connector.
: Go to next step 5).
201
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

DTC DETECTING CONDITION:

Immediately at fault recognition
TROUBLE SYMPTOM:

Failure of engine to start

Engine stalls.

Erroneous idling

Rough driving
WIRING DIAGRAM:
B2M0555
CAUTION:

Check or repair only faulty cylinders.

After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

204
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

B2M0556A
10AA1
CHECK OUTPUT SIGNAL FROM ECM.
1) Turn ignition switch to ON.
2) Measure voltage between ECM connector and chassis
ground on faulty cylinders.
: Connector & terminal
#1 (B84) No. 96 (+)—Chassis ground ():
#2 (B84) No. 70 (+)—Chassis ground ():
#3 (B84) No. 44 (+)—Chassis ground ():
#4 (B84) No. 16 (+)—Chassis ground ():
Is the voltage more than 10 V?
: Go to next.
: Go to step10AA2.
: Is there poor contact in ECM connector?
: Repair poor contact in ECM connector.
: Contact with SOA service.
NOTE:
Inspection by DTM is required, because probable cause is
deterioration of multiple parts.
OBD0713A
10AA2CHECK HARNESS BETWEEN FUEL
INJECTOR AND ECM CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from fuel injector on faulty cylin-
ders.
3) Measure voltage between ECM connector and engine
ground on faulty cylinders.
: Connector & terminal
#1 (E5) No. 1—Engine ground:
#2 (E16) No. 1—Engine ground:
#3 (E6) No. 1—Engine ground:
#4 (E17) No. 1—Engine ground:
Is the resistance less than 10Ω?
: Repair ground short circuit in harness between
fuel injector and ECM connector.
: Go to next step 4).
205
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

B2M0557A
4) Measure resistance of harness connector between
ECM connector and fuel injector on faulty cylinders.
: Connector & terminal
#1 (B84) No. 96—(E5) No. 1:
#2 (B84) No. 70—(E16) No. 1:
#3 (B84) No. 44—(E6) No. 1:
#4 (B84) No. 16—(E17) No. 1:
Is the resistance less than 1Ω?
: Go to step10AA3.
: Repair open circuit in harness between ECM and
fuel injector connector.
G2M0464
10AA3
CHECK FUEL INJECTOR.
Measure resistance between fuel injector terminals on
faulty cylinder.
: Terminals
No. 1—No. 2:
Is the resistance between 5 and 20Ω?
: Replace faulty fuel injector.
: Go to step10AA4.
OBD0715A
10AA4
CHECK POWER SUPPLY LINE.
1) Turn ignition switch to ON.
2) Measure voltage between fuel injector and engine
ground on faulty cylinders.
: Connector & terminal
#1 (E5) No. 2 (+)—Engine ground ():
#2 (E16) No. 2 (+)—Engine ground ():
#3 (E6) No. 2 (+)—Engine ground ():
#4 (E17) No. 2 (+)—Engine ground ():
Is the voltage more than 10 V?
: Repair poor contact in all connectors in fuel injec-
tor circuit.
: Repair harness and connector.
NOTE:
In this case, repair the following:

Open circuit in harness between main relay and fuel
injector connector on faulty cylinders

Poor contact in main relay connector

Poor contact in fuel injector connector on faulty cylinders
206
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles