Page 1208 of 2248
1. General
1. GENERAL DESCRIPTION
The on-board diagnostics (OBD) system detects and
indicates a fault in various inputs and outputs of the com-
plex electronic control. CHECK ENGINE malfunction indi-
cator lamp (MIL) in the combination meter indicates occur-
rence 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 components and the system malfunction
listed in Engine Section which affects on emissions.
When the system decides that a malfunction occurs, MIL
illuminates. At the same time of the MIL illumination or
blinking, a diagnostic trouble code (DTC) and a freeze
frame engine conditions are stored into on-board com-
puter.
The OBD system stores freeze frame engine condition
data (engine load, engine coolant temperature, fuel trim,
engine speed and vehicle speed, etc.) into on-board com-
puter when it detects a malfunction first.
If the OBD system detects the various malfunctions
including the fault of fuel trim or misfire, the OBD system
first stores freeze frame engine conditions about the fuel
trim or misfire.
When the malfunction does not occur again for three
trips, MIL is turned off, but DTC remains at on-board com-
puter.
The OBD-II system is capable of communication with a
general scan tool (OBD-II general scan tool) formed by ISO
9141 CARB.
The OBD-II diagnostics procedure is different from the
usual diagnostics procedure. When troubleshooting OBD-II
vehicles, connect Subaru select monitor or the OBD-II gen-
eral scan tool to the vehicle.
A: ENGINE
1. ENGINE AND EMISSION CONTROL SYSTEM
The Multipoint Fuel Injection (MFI) system is a system
that supplies the optimum air-fuel mixture to the engine for
all the various operating conditions through the use of the
latest electronic technology.
With this system fuel, which is pressurized at a constant
pressure, is injected into the intake air passage of the cyl-
inder head. The injection quantity of fuel is controlled by an
intermittent injection system where the electro-magnetic
injection valve (fuel injector) opens only for a short period
of time, depending on the quantity of air required for one
cycle of operation. In actual operation, the injection quan-
2
2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General
Page 1211 of 2248
1Engine control module (ECM)
2Ignition coil
3Ignitor
4Crankshaft position sensor
5Camshaft position sensor
6Throttle position sensor
7Fuel injectors
8Pressure regulator
9Engine coolant temperature sensor
10Mass air flow sensor
11Idle air control solenoid valve
12Purge control solenoid valve
13Fuel pump
14PCV valve
15Air cleaner
16Canister
17Main relay
18Fuel pump relay
19Fuel filter
20Front catalytic converter
21Rear catalytic converter
22EGR valve
23EGR control solenoid valve
24Radiator fan
25Radiator fan relay
26Pressure sources switching solenoid valve (AT vehicles only)
27Knock sensor
28Back-pressure transducer (AT vehicles only)
29Front oxygen sensor
30Rear oxygen sensor
31Pressure sensor (AT vehicles only)
32A/C compressor
33Inhibitor switch
34CHECK ENGINE malfunction indicator lamp (MIL)
35Tachometer
36A/C relay
37A/C control module
38Ignition switch
39Transmission control module (TCM) (AT vehicles only)
40ABS/TCS control module (TCS equipped models)
41Vehicle speed sensor
42Data link connector (Subaru select monitor)
43Data link connector (OBD-II general scan tool)
44Two way valve
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
1. General
Page 1229 of 2248
3. SENSOR (LHD MODEL)
OBD0041AOBD0042A
OBD0043AOBD0044A
H2M1145COBD0653A
1Vehicle speed sensor 1 (for AT FWD vehicles)
2Vehicle speed sensor 1 (for AT AWD vehicles)
3Vehicle speed sensor 2 (for MT vehicles)
4Vehicle speed sensor 2 (for AT vehicles)
5ATF temperature sensor (for AT vehicles)
6Brake light switch
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
2. Electrical Components Location
Page 1230 of 2248
4. SENSOR (RHD MODEL)
OBD0042BOBD0044B
B2M0464AB2M0437A
1Vehicle speed sensor 1
2Vehicle speed sensor 2
3ATF temperature sensor
4Brake light switch
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
2. Electrical Components Location
Page 1235 of 2248
3. READ DATA LIST
MODE $01
—Current powertrain diagnostic data—
Refers to data denoting the current operating condition of
analog input/output, digital input/output and/or the power-
train system.
A list of the support data and PID (Parameter Identification)
codes are shown in the following table.
PID DataUnit of measure
01 Number of emission-related powertrain trouble codes and MIL 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 pressurekPa
0C Engine revolutionrpm
0D Vehicle speedkm/h
0E Ignition timing advance°
10 Air flow rate from mass air flow sensor g/sec
11 Throttle valve opening angle%
13 Check whether oxygen sensor is installed.—
14 Oxygen sensor output voltage and short term fuel trim associated with oxygen sensor—bank 1 V and %
15 Oxygen sensor output voltage and short term fuel trim associated with oxygen sensor—bank 2 V and %
1C On-board diagnosis system—
NOTE:
Refer to OBD-II general scan tool manufacturer’s instruc-
tion manual to access generic OBD-II PIDs (MODE $01).
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
3. Diagnosis System
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2. READ DATA FUNCTION KEY LIST FOR ENGINE
Function mode Contents Abbreviation Unit of measure
F00 ROM ID number YEAR—
F01 Battery voltage VB V
F02 Vehicle speed signal VSP m/h
F03 Vehicle speed signal VSP km/h
F04 Engine speed signal EREV rpm
F05 Engine coolant temperature signal TW°F
F06 Engine coolant temperature signal TW°C
F07 Ignition signal ADVS deg
F08 Mass air flow signal QA V
F09 Load data DATA—
F10 Throttle position signal THV V
F11 Injector pulse width TIM mS
F12 Idle air control signal ISC %
F13 Front oxygen sensor output signal FO2 V
F14 Front oxygen sensor maximum output signal FO2max V
F15 Front oxygen sensor minimum output signal FO2min V
F16 Rear oxygen sensor output signal RO2 V
F17 Rear oxygen sensor maximum output signal RO2max V
F18 Rear oxygen sensor minimum output signal RO2min V
F19 Short term fuel trim ALPHA %
F20 Knock sensor signal RTRD deg
F21 A/F correction (short term trim) by rear oxygen sensor PHOS %
F23 Atmospheric absolute pressure signal (AT vehicles) BARO. P V
F24 Intake manifold absolute pressure signal (AT vehicles) MANI. P V
F25 Long term fuel trim KBLRC %
F28 Long term whole fuel trim K0 %
F29 Front oxygen sensor heater current FO2H A
F30 Rear oxygen sensor heater current RO2H A
F33Maximum value of cylinder #1 misfire times during 200
rotationsMF1 %
F34Maximum value of cylinder #2 misfire times during 200
rotationsMF2 %
F35Maximum value of cylinder #3 misfire times during 200
rotationsMF3 %
F36Maximum value of cylinder #4 misfire times during 200
rotationsMF4 %
F37 Maximum EGR system pressure value (AT vehicles) EGRmax mmHg
F38 Minimum EGR system pressure value (AT vehicles) EGRmin mmHg
F45 Load data LOAD %
F46 Throttle position signal THV %
F47 Mass air flow signal QA g/s
F48 Atmospheric absolute pressure signal BARO. P kPa
F49 Intake manifold absolute pressure signal MANI. P kPa
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
3. Diagnosis System
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3. FA MODE FOR ENGINE
Function
modeLED No. Contents Display LED“ON”requirements
FA 01 Ignition switch IG When ignition switch is turned ON.
2 AT/MT identification signal AT When AT identification signal is entered.
3 Test mode connector UD When test mode connector is connected.
5 Idle speed control identification signal ICWhen engine rpm is less than the established
value.
7 Neutral switch NT When neutral position signal is entered.
FA 12 Air conditioner switch AC When air conditioner switch is turned ON.
3 Air conditioner relay AR When air conditioner relay is in function.
4 Radiator fan relay 1 R1 When radiator fan relay 1 is in function.
5 Radiator fan relay 2 R2 When radiator fan relay 2 is in function.
6 Fuel pump relay FP When fuel pump relay is in function.
7 Purge control solenoid valve CP When purge control solenoid valve is in function.
9 Pressure sources switching solenoid valve BRWhen pressure sources switching solenoid valve
is in function.
FA 23 EGR solenoid valve EG When EGR solenoid valve is in function.
4 Engine torque control signal TR When engine torque control signal is entered.
5 Engine torque control cut signal TC When engine torque control cut signal is got out.
9 Front oxygen sensor signal FO When front oxygen sensor mixture ratio is rich.
10 Rear oxygen sensor signal RO When rear oxygen sensor mixture ratio is rich.
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
3. Diagnosis System
Page 1257 of 2248
6. READ DATA FUNCTION KEY LIST FOR AT
Function mode Contents Abbr. Unit
F00 Mode display——
F01 Battery voltage VB V
F02 Vehicle speed sensor 1 VSP1 m/h
F03 Vehicle speed sensor 1 VSP1 km/h
F04 Vehicle speed sensor 2 VSP2 m/h
F05 Vehicle speed sensor 2 VSP2 km/h
F06 Engine speed EREV rpm
F07 ATF temperature sensor ATFT deg F
F08 ATF temperature sensor ATFT deg C
F09 Throttle position sensor THV V
F10 Gear position GEAR—
F11 Line pressure duty PLDTY %
F12 Lock-up duty LUDTY %
F13 AWD duty 4WDTY %
F14 Throttle position sensor power supply THVCC V
F15 Mass air flow sensor AFM V
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
3. Diagnosis System
