1995 SUBARU LEGACY engine

OBD0145A
B2M0271
OBD0616
1CONNECT 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
the OBD-II general scan tool switch to ON.
4) Start engine.
5) Read data on Subaru Select Monitor or OBD-II general
scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F08 or F47

F08: Voltage input from mass air flow sensor is shown
on display.

F47: Mass air flow is shown on display.

F08: Is sensor output equal to or more
than 0.3 V and equal to or less than
5.0 V?

F47: Is sensor output equal to or more
than 1.3 g/sec and equal to or less
than 250 g/sec?
Probable cause: Poor connect of connectors, circuit and
grounding line.
: Even if MIL lights up, the circuit has returned to a
normal condition at this time. A temporary poor
contact of the connector or harness may be the
cause. Repair harness or connector of the mass
air flow sensor.
HINT:
1Open or short circuit between mass air flow sen-
sor and ECM.

2Poor contact of connectors for mass air flow sen-
sor or ECM.
: Go to next.
: Is the value less than 0.3 V (1.3 g/sec)?
: Go to step 2.
: Go to step 5.

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
138
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

OBD0689A
2CHECK INPUT SIGNAL FOR ECM. (USING
VOLTAGE METER AND SUBARU SELECT
MONITOR.)
Measure voltage between ECM and body while engine is
idling.
: Connector & terminal
(B84) No. 26—Body/0.3 V, or less
: Go to step 3.
: Go to next.
G2M0527
: Is the voltage more than 0.3 V while shaking
harness and connector of ECM and monitor-
ing the value with Subaru select monitor?
: Repair poor contact in ECM connector.
: Replace ECM with a new one.
B2M0623A
3CHECK POWER SUPPLY TO MASS AIR
FLOW SENSOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from mass air flow sensor.
3) Turn ignition switch to ON.
4) Measure voltage between mass air flow sensor connec-
tor and body.
: Connector & terminal
(B3) No. 1—Body/10 V, or more
: Go to step 4.
: Repair open circuit of harness between main relay
connector and mass air flow sensor connector.
139
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

OBD0152
C: DTC P0101
—MASS AIR FLOW SENSOR CIRCUIT
RANGE/PERFORMANCE PROBLEM (QA
—R)
—
DESCRIPTION:
Refer to“B: DTC P0100—MASS AIR FLOW SENSOR
CIRCUIT MALFUNCTION—[T11B0]”.
DTC DETECTING CONDITION:

Two consecutive trips with fault
TROUBLE SYMPTOM:

Erroneous idling

Engine stalls.

Poor driving performance
141
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

OBD0154
D: DTC P0105
—PRESSURE SENSOR CIRCUIT
MALFUNCTION (P
—S)—
OBD0155A
DESCRIPTION:
The pressure sensor is used in AT vehicles. It is located in
the engine compartment, at the front of the right-hand sus-
pension. It consists of a solenoid, which switches between
the atmospheric pressure and suction pressure lines and a
pressure sensor. This arrangement allows either pressure
line to be monitored.
A sensor output signal is sent to the ECM to diagnose the
EGR system and evaporative emission control system.
(The pressure sensor is not used in MT vehicles.)
DTC DETECTING CONDITION:

Immediately at fault recognition
144
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

1
CHECK TRANSMISSION TYPE.
Refer to the flow chart on page 145.
OBD0145A
OBD0620
OBD0641
2CONNECT 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
the OBD-II general scan tool switch to ON.
4) Start engine.
5) Read the data on Subaru Select Monitor or the OBD-II
general scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F24 or F49

F24: Display shows voltage signal value sent from pres-
sure sensor.

F49: Display shows pressure signal value sent from
pressure sensor.
: Less than 0.2 V or 0 kPa
: Go to step 3.
: Go to next.
: More than 4.9 V or 140 kPa
: Go to step 5.
: Repair the harness and connector between pres-
sure sensor and ECM.
HINT:
1Open or short circuit of harness between pres-
sure sensor and ECM.

2Poor contact of pressure sensor connector and
ECM connector.

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
147
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:

RHD model
B2M0449
1
CHECK TRANSMISSION TYPE.
Refer to the flow chart on page 151.
2
CHECK DTC P0105 OR P1102 ON DISPLAY.
Refer to the flow chart on page 151.
OBD0145A
3
CHECK DATA FOR CONTROL.
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 ON and Subaru Select Monitor or
the OBD-II general scan tool switch ON.
4) Start engine.
153
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

OBD0172
F: DTC P0115
—ENGINE COOLANT TEMPERATURE
SENSOR CIRCUIT MALFUNCTION (TW)—
OBD0173A
DESCRIPTION:
The engine coolant temperature sensor is located on the
engine coolant pipe which is made of aluminum alloy. Its
thermistor changes resistance with respect to temperature.
A engine coolant temperature signal converted into resis-
tance is transmitted to the ECM to control the amount of
fuel injection, ignition timing, purge control solenoid valve,
etc.
DTC DETECTING CONDITION:

Immediately at fault recognition
TROUBLE SYMPTOM:

Hard to start

Erroneous idling

Poor driving performance
156
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code

OBD0145A
1CONNECT 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.
OBD0176
OBD0177
5) Read data on Subaru Select Monitor or OBD-II general
scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F05 or F06

F05: Water temperature is indicated in“°F”.

F06: Water temperature is indicated in“°C”.
:
Is the value greater than 300°F with func-
tion mode F05?

Is the value greater than 150°C with func-
tion mode F06?
: Go to step 2.
: Go to next.
:
Is the value less than 40°F with function
mode F05?

Is the value less than 40°C with function
mode F06?
: Go to step 3.
: Repair poor contact in connectors or harness.

Engine coolant temperature sensor connector

ECM connector

Coupling connector (B21)

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
OBD0618A
2
CHECK HARNESS.
1) Turn ignition switch to OFF.
2) Remove idle air control solenoid valve by-pass air hose.
3) Disconnect connector from engine coolant temperature
sensor.
158
2-7ON-BOARD DIAGNOSTICS II SYSTEM
11. Diagnostics Chart with Trouble Code