
EN(H4SO)-7
ENGINE (DIAGNOSTIC)
General Description
The antenna feeder must be placed as far
apart as possible from the ECM and MFI har-
ness.
Carefully adjust the antenna for correct
matching.
When mounting a large power type radio, pay
special attention to the three items above men-
tioned.
Incorrect installation of the radio may affect
the operation of the ECM.
13) Before disconnecting the fuel hose, disconnect
the fuel pump connector and crank the engine for
more than five seconds to release pressure in the
fuel system. If engine starts during this operation,
run it until it stops.
14) Problems in the electronic-controlled automatic
transmission may be caused by failure of the en-
gine, the electronic control system, the transmis-
sion proper, or by a combination of these. These
three causes must be distinguished clearly when
performing diagnostics.
15) Diagnostics should be conducted by rotating
with simple, easy operations and proceeding to
complicated, difficult operations. The most impor-
tant thing in diagnostics is to understand the cus-
tomer’s complaint, and distinguish between the
three causes.
16) In AT models, do not continue the stall for more
than five seconds. (from closed throttle, fully open
throttle to stall engine speed.)
17) On the model with ABS, when performing driv-
ing test in jacked-up or lifted-up position, some-
times the warning light may be lit, but this is not a
malfunction of the system. The reason for this is the
speed difference between the front and rear
wheels. After diagnosis of engine control system,
perform the ABS memory clearance procedure of
self-diagnosis function.
B: INSPECTION
Before performing diagnostics, check the following
items which might affect engine problems:
1. BATTERY
1) Measure battery voltage and specific gravity of
electrolyte.
Standard voltage: 12 V
Specific gravity: Above 1.260
2) Check the condition of the main and other fuses,
and harnesses and connectors. Also check for
proper grounding.
2. ENGINE GROUND
Make sure the engine grounding terminal is proper-
ly connected to the engine.
C: NOTE
1. GENERAL DESCRIPTION
On-board diagnosis (OBD) system detects and
indicates a fault in various inputs and outputs of the
complex electronic control. Malfunction indicator
light in the combination meter indicates occurrence
of a fault or trouble.
Further, against such a failure or sensors as may
disable the drive, the fail-safe function is provided
to ensure the minimal driveability.
The OBD system incorporated with the vehicles
within this engine family complies with Section
1968.1, California Code of Regulations (OBD-II
regulation). The OBD system monitors the compo-
nents and the system malfunction listed in Engine
Section which affects on emissions.
When the system decides that a malfunction oc-
curs, malfunction indicator light illuminates. At the
same time of the malfunction indicator light illumi-
nation or blinking, the DTC and a freeze frame en-
gine conditions are stored into on-board computer.
The OBD system stores freeze frame engine
condition data (engine load, engine coolant tem-
perature, fuel trim, engine speed and vehicle
speed, etc.) into on-board computer when it detects
a malfunction first.
If the OBD system detects the various malfunc-
tions including the fault of fuel trim or misfire, the
OBD system first stores freeze frame engine condi-
tions about the fuel trim or misfire.
When the malfunction does not occur again for
three consecutive driving cycles, malfunction indi-
cator light is turned off, but DTC remains at on-
board computer.
The OBD-II system is capable of communication
with a general scan tool (OBD-II general scan tool)
formed by ISO 9141 CARB.
EN-00153

EN(H4SO)-8
ENGINE (DIAGNOSTIC)
General Description
The OBD-II diagnostics procedure is different
from the usual diagnosis procedure. When trouble-
shooting the OBD-II models, connect Subaru Se-
lect Monitor or the OBD-II general scan tool to the
vehicle.
2. ENGINE AND EMISSION CONTROL SYS-
TEM
MFI system is a system that supplies the opti-
mum air-fuel mixture to the engine for all the vari-
ous operating conditions through the use of the
latest electronic technology.
With this system fuel, which is pressurized at a con-
stant pressure, is injected into the intake air pas-
sage of the cylinder head. The injection quantity of
fuel is controlled by an intermittent injection system
where the electro-magnetic injection valve (fuel in-
jector) opens only for a short period of time, de-
pending on the quantity of air required for one cycle
of operation. In actual operation, the injection quan-
tity is determined by the duration of an electric sig-
nal applied to the fuel injector and this permits
simple, yet highly precise metering of the fuel.
Further, all the operating conditions of the engine
are converted into electric signals, and this results
in additional features of the system, such as large
improved adaptability, easier addition of compen-
sating element, etc.The MFI system also has the following features:
Reduced emission of harmful exhaust gases.
Reduced in fuel consumption.
Increased engine output.
Superior acceleration and deceleration.
Excellent engine start and warm-up perfor-
mance by the correction of engine coolant tem-
perature and intake air temperature.3. AUTOMATIC TRANSMISSION AND
ELECTRONIC-HYDRAULIC CONTROL SYS-
TEM
The electronic-hydraulic control system consists of
various sensors and switches, TCM and the hy-
draulic controller including solenoid valves. The
system controls the transmission body including
shift control, lock-up control, overrunning clutch
control, line pressure control and shift timing con-
trol. It also controls the AWD transfer clutch. In oth-
er words, the system detects various operating
conditions from various input signals and sends
output signals to shift solenoids 1, 2 and low clutch
timing solenoid and 2-4 brake timing solenoid, line
pressure duty solenoid, lock-up duty solenoid,
transfer duty solenoid and 2-4 brake duty solenoid
(a total of eight solenoids).
D: PREPARATION TOOL
ILLUSTRATION TOOL NUMBER DESCRIPTION REMARKS
24082AA230
(Newly adopted tool)CARTRIDGE Troubleshooting for electrical system.
22771AA030 SUBARU SELECT
MONITOR KITTroubleshooting for electrical system.
English: 22771AA030 (Without printer)
German: 22771AA070 (Without printer)
French: 22771AA080 (Without printer)
Spanish: 22771AA090 (Without printer)
ST24082AA230
ST22771AA030

EN(H4SO)-27
ENGINE (DIAGNOSTIC)
OBD-II General Scan Tool
9. OBD-II General Scan Tool
A: OPERATION
1. HOW TO USE OBD-II GENERAL SCAN
TOOL
1) Prepare a general scan tool (OBD-II general
scan tool) required by SAE J1978.
2) Connect the OBD-II general scan tool to its data
link connector in the lower portion of the instrument
panel (on the driver’s side).3) Using the OBD-II general scan tool, call up the
DTC and freeze frame data.
OBD-II general 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
DTC
(4) MODE $04: Clear/Reset emission-related
diagnostic information
Read out data according to repair procedures. (For
detailed operation procedures, refer to the OBD-II
General Scan Tool Operation Manual.)
NOTE:
For details concerning DTCs, refer to the List of Di-
agnostic Trouble Code (DTC).
2. MODE $01 (CURRENT POWERTRAIN DIAGNOSTIC DATA)
Refers to data denoting the current operating condition of analog input/output, digital input/output and/or the
powertrain system.
A list of the support data and PID (Parameter Identification) codes are shown in the following table.
NOTE:
Refer to OBD-II general scan tool manufacturer’s instruction manual to access generic OBD-II PIDs (MODE
$01).
ME-00325
PID Data Unit of measure
01 Number of emission-related powertrain DTC and malfunction indicator light status ON/OFF
03 Fuel system control status—
04 Calculated engine load value%
05 Engine coolant temperature°C
06 Short term fuel trim%
07 Long term fuel trim%
0B Intake manifold absolute pressure kPa
0C Engine speedrpm
0D Vehicle speedkm/h
0E Ignition timing advance°
10 Air flow rate of manifold absolute pressure sensor g/sec
11 Throttle valve opening angle%
13 Check whether oxygen sensor is installed. —
14Oxygen sensor output voltage and short term fuel trim — bank 1 associated with oxygen sen-
sorV and%
15Oxygen sensor output voltage and short term fuel trim — bank 2 associated with oxygen sen-
sorV and %
1C On-board diagnostic system—

EN(H4SO)-28
ENGINE (DIAGNOSTIC)
OBD-II General Scan Tool
3. MODE $02 (POWERTRAIN FREEZE FRAME DATA)
Refers to data denoting the operating condition when trouble is sensed by the on-board diagnosis system.
A list of the support data and PID (Parameter Identification) codes are shown in the following table.
NOTE:
Refer to OBD-II general scan tool manufacturer’s instruction manual to access freeze frame data (MODE
$02).
4. MODE $03 (EMISSION-RELATED POWERTRAIN DIAGNOSTIC TROUBLE CODES)
Refer to “Read Diagnostic Trouble Code (DTC)” for information about data denoting emission-related pow-
ertrain DTC.
5. MODE $04 (CLEAR/RESET EMISSION-RELATED DIAGNOSTIC INFORMATION)
Refers to the mode used to clear or reset emission-related diagnostic information (OBD-II trouble diagnostic
information).
NOTE:
Refer to OBD-II general scan tool manufacturer’s instruction manual to clear or reset emission-related diag-
nostic information (MODE $04).
PID Data Unit of measure
02 DTC that caused CARB required freeze frame data storage —
03 Fuel system control status—
04 Calculated engine load value%
05 Engine coolant temperature°C
06 Short term fuel trim%
07 Long term fuel trim%
0B Intake manifold absolute pressure kPa
0C Engine speedrpm
0D Vehicle speedkm/h
![SUBARU FORESTER 2004 Service Repair Manual EN(H4SO)-30
ENGINE (DIAGNOSTIC)
Subaru Select Monitor
4. READ CURRENT DATA FOR ENGINE. (NORMAL MODE)
1) On the «Main Menu» display screen, select the {Each System Check} and press the [YES] key.
2) SUBARU FORESTER 2004 Service Repair Manual EN(H4SO)-30
ENGINE (DIAGNOSTIC)
Subaru Select Monitor
4. READ CURRENT DATA FOR ENGINE. (NORMAL MODE)
1) On the «Main Menu» display screen, select the {Each System Check} and press the [YES] key.
2)](/manual-img/17/57426/w960_57426-1127.png)
EN(H4SO)-30
ENGINE (DIAGNOSTIC)
Subaru Select Monitor
4. READ CURRENT DATA FOR ENGINE. (NORMAL MODE)
1) On the «Main Menu» display screen, select the {Each System Check} and press the [YES] key.
2) On the «System Selection Menu» display screen, select the {Engine} and press the [YES] key.
3) Press the [YES] key after the information of engine type was displayed.
4) On the «Engine Diagnosis» display screen, select the {Current Data Display/Save}, and then press the
[YES] key.
5) On the «Data Display Menu» display screen, select the {Data Display} and press the [YES] key.
6) Using the scroll key, scroll the display screen up or down until the desired data is shown.
A list of the support data is shown in the following table.
Description Display Unit of measure
Battery voltage Battery Voltage V
Vehicle speed signal Meter vehicle speed km/h or MPH
Engine speed signal Engine speed rpm
Engine coolant temperature signal Engine coolant temperature°C or (°F)
Ignition timing signal Ignition timing deg
Throttle position signal Amount of intake air %
Throttle position signal Throttle Sensor Voltage V
Injection pulse width Fuel injection pulse width ms
Idle air control signal ISC Steps STEP
Engine load data Engine load %
Front oxygen (A/F) sensor resistance A/F sensor resistance value 1 ohm
Front oxygen (A/F) sensor output signal A/F sensor current value 1 —
Rear oxygen sensor output signalRear oxygen sensor voltage
valueV
Short term fuel trim A/F Compensation 1 %
Knock sensor signal Knock Correction deg
Atmospheric absolute pressure signal Atmospheric pressure mmHg, kPa, inHg or psi
Intake manifold relative pressure signal Mani. Relative Pressure mmHg, kPa, inHg or psi
Intake manifold absolute pressure signalIntake manifold absolute pres-
suremmHg, kPa, inHg or psi
A/F correction (short term fuel trim) by rear oxygen sensor A/F Compensation 3 %
Long term whole fuel trim A/F learning 1 %
Front oxygen (A/F) sensor heater current Front O2 heater current value A
Rear oxygen sensor heater current Rear O2 heater current value A
Canister purge control solenoid valve duty ratio CPC Valve Duty Ratio %
Fuel level signal Fuel level voltage V
Intake air temperature signal Intake air temperature°C or (°F)
Learned ignition timing Ignition learning value deg
EGR signal EGR Steps STEP
Ignition switch signal Ignition SW ON or OFF
Test mode connector signal Test mode signal ON or OFF
Neutral position switch signal Neutral SW ON or OFF
Air conditioning switch signal A/C SW ON or OFF
Air conditioning compressor signal A/C Compressor Signal ON or OFF
Radiator main fan relay signal Radiator fan relay 1 ON or OFF
Fuel pump relay signal Fuel pump relay ON or OFF
Knocking signal Knock signal ON or OFF
Radiator sub fan relay signal Radiator fan relay 2 ON or OFF
Power steering switch signal Power steering SW input signal ON or OFF
Engine torque control signal #1 AT coordinate request signal 1 ON or OFF
Engine torque control signal #2 AT coordinate request signal 2 ON or OFF
![SUBARU FORESTER 2004 Service Repair Manual EN(H4SO)-32
ENGINE (DIAGNOSTIC)
Subaru Select Monitor
5. READ CURRENT DATA FOR ENGINE (OBD MODE)
1) On the «Main Menu» display screen, select the {Each System Check} and press the [YES] key.
2) On t SUBARU FORESTER 2004 Service Repair Manual EN(H4SO)-32
ENGINE (DIAGNOSTIC)
Subaru Select Monitor
5. READ CURRENT DATA FOR ENGINE (OBD MODE)
1) On the «Main Menu» display screen, select the {Each System Check} and press the [YES] key.
2) On t](/manual-img/17/57426/w960_57426-1129.png)
EN(H4SO)-32
ENGINE (DIAGNOSTIC)
Subaru Select Monitor
5. READ CURRENT DATA FOR ENGINE (OBD MODE)
1) On the «Main Menu» display screen, select the {Each System Check} and press the [YES] key.
2) On the «System Selection Menu» display screen, select the {Engine} and press the [YES] key.
3) Press the [YES] key after the information of engine type was displayed.
4) On the «Engine Diagnosis» display screen, select the {OBD system} and press the [YES] key.
5) On the «OBD Menu» display screen, select the {Current Data Display & Save}, and press the [YES] key.
6) On the «Data Display Menu» display screen, select the {Data Display} and press the [YES] key.
7) Using the scroll key, scroll the display screen up or down until the desired data is shown.
A list of the support data is shown in the following table.
NOTE:
For detailed operation procedure, refer to the “SUBARU SELECT MONITOR OPERATION MANUAL”.
Description Display Unit of measure
Number of DTC Number of diagnosis code —
Condition of malfunction indicator light MI (MIL) ON or OFF
Monitoring test of misfire Misfire Monitoring Complete or incomplete
Monitoring test of fuel system Fuel System Diagnosis Complete or incomplete
Monitoring test of comprehensive component Component Diagnosis Complete or incomplete
Test of catalyst Catalyst diagnosis Complete or incomplete
Test of heating-type catalyst Heated catalyst diagnosis No support
Test of evaporative emission purge control system Evap. purge diagnosis Complete or incomplete
Test of secondary air system Secondary air diagnosis No support
Test of air conditioning system refrigerant A/C refrigerant diagnosis No support
Test of oxygen sensor O2 sensor diagnosis Complete or incomplete
Test of oxygen sensor heater O2 heater diagnosis Complete or incomplete
Test of EGR system EGR diagnosis —
Air fuel ratio control system for bank 1 Fuel System for bank 1 —
Engine load data Engine load %
Engine coolant temperature signal Engine coolant temperature°C or (°F)
Short term fuel trim by front oxygen (A/F) sensor Short term fuel trim B1 %
Long term fuel trim by front oxygen (A/F) sensor Long term fuel trim B1 %
Intake manifold absolute pressure signalIntake manifold absolute pres-
suremmHg, kPa, inHg or psi
Engine speed signal Engine speed rpm
Vehicle speed signal Meter vehicle speed km/h or MPH
Ignition timing advance for #1 cylinder Ignition timing adv. #1°
Intake air temperature signal Intake air temperature°C or (°F)
Amount of intake air Amount of intake air g/s
Throttle position signal Throttle valve angle %
Rear oxygen sensor output signal O2 sensor #12 V
Air fuel ratio correction by rear oxygen sensor Short term fuel trim #12 %
On-board diagnostic system OBD system —
Oxygen sensor #11 O2 sensor #11 With support
Oxygen sensor #12 O2 sensor #12 With support
A/F sensor #11 A/F sensor #11 —
![SUBARU FORESTER 2004 Service Repair Manual EN(H4SO)-33
ENGINE (DIAGNOSTIC)
Subaru Select Monitor
6. READ FREEZE FRAME DATA FOR ENGINE. (OBD MODE)
1) On the «Main Menu» display screen, select the {Each System Check} and press the [YES] key.
SUBARU FORESTER 2004 Service Repair Manual EN(H4SO)-33
ENGINE (DIAGNOSTIC)
Subaru Select Monitor
6. READ FREEZE FRAME DATA FOR ENGINE. (OBD MODE)
1) On the «Main Menu» display screen, select the {Each System Check} and press the [YES] key.](/manual-img/17/57426/w960_57426-1130.png)
EN(H4SO)-33
ENGINE (DIAGNOSTIC)
Subaru Select Monitor
6. READ FREEZE FRAME DATA FOR ENGINE. (OBD MODE)
1) On the «Main Menu» display screen, select the {Each System Check} and press the [YES] key.
2) On the «System Selection Menu» display screen, select the {Engine} and press the [YES] key.
3) Press the [YES] key after the information of engine type was displayed.
4) On the «Engine Diagnosis» display screen, select the {OBD System} and press the [YES] key.
5) On the «OBD Menu» display screen, select the {Freeze Frame Data} and press the [YES] key.
A list of the support data is shown in the following table.
NOTE:
For detailed operation procedure, refer to the SUBARU SELECT MONITOR OPERATION MANUAL.
Description Display Unit of measure
DTC of freeze frame data Freeze frame data DTC
Air fuel ratio control system for bank 1 Fuel system for Bank 1 ON or OFF
Engine load data Engine load %
Engine coolant temperature signal Engine coolant temperature°C or (°F)
Short term fuel trim by front oxygen (A/F) sensor Short term fuel trim B1 %
Long term fuel trim by front oxygen (A/F) sensor Long term fuel trim B1 %
Intake manifold absolute pressure signalIntake manifold absolute pres-
suremmHg, kPa, inHg or psi
Engine speed signal Engine speed rpm
Vehicle speed signal Meter vehicle speed km/h or MPH

EN(H4SO)-47
ENGINE (DIAGNOSTIC)
Malfunction Indicator Light
16.Malfunction Indicator Light
A: PROCEDURE
B: ACTIVATION OF MALFUNCTION
INDICATOR LIGHT
1) When the ignition switch is turned to ON (engine
off), the malfunction indicator light (1) in the combi-
nation meter illuminates.
NOTE:
If the malfunction indicator light does not illuminate,
perform the diagnosis of malfunction indicator light
circuit or the combination meter circuit.
LIGHT DOES NOT COME ON, Malfunction Indica-
tor Light.>2) After starting the engine, the malfunction indica-
tor light goes out. If it does not, either the engine or
the emission control system is malfunctioning.
1. Activation of malfunction indicator light.
↓
2. Check that the malfunction indicator light does not come on.
↓
3. Check that the malfunction indicator light does not go off.
↓
4. Check that the malfunction indicator light does not blink.
↓
5. Check that the malfunction indicator light remains blinking.
EN-00950(1)
(1) No faulty
(2) Trouble occurs
(3) ON
(4) OFF
(5) Ignition switch ON
(6) Engine start
EN-01679
(1)
(2)
(5)
(6)(3)
(4)
(3)
(4)