Subaru Legacy III (2000-2003 year). Manual - part 228

EN(H4SOw/oOBD)-102

ENGINE (DIAGNOSTICS)

GENERAL DIAGNOSTIC TABLE

15.General Diagnostic Table

A: INSPECTION

NOTE:
• Malfunction of parts other than those listed is also possible.
• The right-hand priority column indicates the inspection priority of probable causes of the symptom. Carry
out the check starting from A.

Symptom

Problem parts

Priority

1. Engine does not start. (internal combustion does
not occur.)

1) ECM power supply
2) Engine ground terminal
3) Crankshaft position sensor
4) Camshaft position sensor
5) Fuel pump
6) Pressure regulator
7) Ignition coil & ignitor
8) Spark plug
9) Fuel injector

A
A
B
B
B
B
C
C
C

2. Engine does not start. (internal combustion
occurs.)

1) ECM power supply
2) Spark plug
3) Engine coolant temperature sensor
4) Pressure regulator
5) Pressure sensor
6) Fuel pump
7) Fuel injector
8) Camshaft position sensor
9) Crankshaft position sensor
10) Idle air control solenoid valve

A
A
B
B
C
C
C
C
C
C

3. Engine does not start. (engine stalls after internal
combustion.)

1) ECM power supply
2) Pressure sensor
3) Engine coolant temperature sensor
4) Spark plug
5) Ignition coil
6) Fuel pump
7) Pressure regulator
8) Fuel injector
9) Idle air control solenoid valve

A
A
B
B
C
C
C
C
C

4. Engine stalls.

1) Idle air control solenoid valve
2) Pressure sensor
3) Spark plug
4) Accelerator cable is out of adjustment
5) ECM power supply
6) Throttle position sensor
7) Crankshaft position sensor
8) Vehicle speed sensor
9) Ignition coil
10) Fuel pump

A
B
B
B
C
C
C
C
C
C

EN(H4SOw/oOBD)-103

ENGINE (DIAGNOSTICS)

GENERAL DIAGNOSTIC TABLE

5. Rough idling

1) Spark plug
2) Pressure sensor
3) Engine coolant temperature sensor
4) Pressure regulator
5) Idle air control solenoid valve
6) Air leak in air intake system
7) ECM power supply
8) Throttle position sensor
9) Camshaft position sensor
10) Crankshaft position sensor
11) Oxygen sensor
12) Fuel pump
13) Fuel injector
14) Test mode or read memory connectors are con-
nected.
15) Intake air temperature sensor

A
B
B
B
B
B
C
C
C
C
C
C
C
C

6. Hard to drive at constant speed

1) Pressure regulator
2) Fuel injector
3) Pressure sensor
4) Engine coolant temperature sensor
5) Throttle position sensor
6) Fuel pump

A
B
C
C
C
C

7. Poor acceleration/deceleration

1) Spark plug
2) Throttle position sensor
3) Ignition coil
4) Fuel pump
5) Pressure regulator
6) Fuel injector
7) Pressure sensor
8) Engine coolant temperature sensor
9) Idle air control solenoid valve
10) Knock sensor

A
B
B
B
B
B
C
C
C
C

8. Poor return to idling

1) Accelerator cable is out of adjustment
2) Throttle position sensor
3) Idle air control solenoid valve
4) Pressure sensor
5) Engine coolant temperature sensor

A
B
B
C
C

9. Back fire

1) Spark plug
2) Fuel injector
3) Ignition coil and ignitor
4) Fuel pump
5) Pressure regulator

A
B
C
C
C

10. Knocking

1) Pressure sensor
2) Fuel pump
3) Knock sensor
4) Pressure regulator
5) Engine coolant temperature sensor

A
B
B
B
C

11. Excessive fuel consumption

1) Pressure sensor
2) Pressure regulator

A
B

12. Shocks while driving

1) Pressure regulator
2) ECM power supply
3) Throttle position sensor

A
B
B

13. Poor engine revving

1) Pressure regulator
2) Pressure sensor
3) Engine coolant temperature sensor
4) Throttle sensor
5) Fuel pump

A
B
B
B
B

Symptom

Problem parts

Priority

EN(H4SOw/oOBD)-104

ENGINE (DIAGNOSTICS)

GENERAL DIAGNOSTIC TABLE

A*: Including ECM ground circuit
B*: Check hoses.

14. Remarks

1) ECM power supply
2) Pressure sensor
3) Pressure regulator
4) Idle air control solenoid valve
5) Air leak in air intake system

A*
B*
B*
B*
B*

Symptom

Problem parts

Priority

FUJI HEAVY INDUSTRIES LTD.

G2300GE3

2003 LEGACY SERVICE MANUAL

QUICK REFERENCE INDEX

ENGINE SECTION 2

This service manual has been prepared
to provide SUBARU service personnel
with the necessary information and data
for the correct maintenance and repair
of SUBARU vehicles.
This manual includes the procedures
for maintenance, disassembling, reas-
sembling, inspection and adjustment of
components and diagnostics for guid-
ance of experienced mechanics.
Please peruse and utilize this manual
fully to ensure complete repair work for
satisfying our customers by keeping
their vehicle in optimum condition.
When replacement of parts during
repair work is needed, be sure to use
SUBARU genuine parts.

All information, illustration and specifi-
cations contained in this manual are
based on the latest product information
available at the time of publication
approval.

FUEL INJECTION (FUEL SYSTEMS)

FU(H6DO)

EMISSION CONTROL
(AUX. EMISSION CONTROL DEVICES)

EC(H6DO)

INTAKE (INDUCTION)