2004 SUBARU FORESTER oxygen

EN(H4DOTC 2.5)-25
ENGINE (DIAGNOSTIC)
OBD-II General Scan Tool
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).
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).
PID Data Unit of measure
01Number of emission-related powertrain DTC, malfunction indicator light status and diagnosis
support information—
03 Fuel system control status—
04 Calculated engine load value%
05 Engine coolant temperature°C
06 Short term fuel trim%
07 Long term whole fuel trim%
0B Intake manifold absolute pressure kPa, mmHg
0C Engine revolutionrpm
0D Vehicle speedkm/h
0E Ignition timing advance°
0F Intake air temperature°C
10 Air flow rate of mass air flow sensor g/sec
11 Throttle valve absolute opening angle %
13 Check whether oxygen sensor is installed. —
15 Oxygen sensor output voltage and short term fuel trim associated with oxygen sensor V and %
1C Available OBD system—
24 A/F value and A/F sensor output voltage — and V
34 A/F value and A/F sensor current — and mA
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 whole fuel trim%
0B Intake manifold absolute pressure mmHg
0C Engine speedrpm
0D Vehicle speedkm/h
0E Ignition timing advance°
0F Intake air temperature°C
10 Air flow rate of mass air flow sensor g/sec
11 Throttle valve absolute opening angle %

EN(H4DOTC 2.5)-28
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» screen, select the {Current Data Display/Save}, and then press the [YES] key.
5) On the «Data Display Menu» screen, select the {Data Display} and press the [YES] key.
6) Using the scroll key, move the display screen up or down until the desired data is shown.
 A list of the support data is shown in the following table.
Remarks Display Unit of measure
Battery voltage Battery Voltage V
Vehicle speed signal Vehicle Speed km/h or MPH
Engine speed signal Engine Speed rpm
Engine coolant temperature signal Coolant Temp.°C or °F
Ignition timing signal Ignition Timing deg
Throttle position signal Throttle Opening Angle %
Injection pulse width Fuel Injection #1 Pulse ms
Fuel pump duty control signal Fuel Pump Duty %
A/F sensor current A/F Sensor #1 Current mA
A/F sensor resistance A/F Sensor #1 ResistanceΩ
Front oxygen (A/F) sensor lambda value A/F Sensor #1 —
Rear oxygen sensor output signalRear O
2 Sensor
V
Short term fuel trim A/F Correction #1 %
Knock sensor compensation Knocking Correction deg
Atmospheric pressure signal Atmosphere Pressure mmHg, kPa, inHg or psi
Intake manifold relative pressure signal Mani. Relative Pressure mmHg, kPa, inHg or psi
Intake manifold absolute pressure signal Mani. Absolute Pressure mmHg, kPa, inHg or psi
A/F correction (short term fuel trim) by rear oxygen sensor A/F Correction #3 %
Long term whole fuel trim A/F Learning #1 %
Canister purge control solenoid valve duty ratio CPC Valve Duty Ratio %
Primary supercharged pressure control signal Primary Control %
Tumble generated valve position sensor signal (RH side) TGV Position Sensor R V
Tumble generated valve position sensor signal (LH side) TGV Position Sensor L V
Acceleration opening angle Accel Opening Angle %
VVT advance angle amount (R) VVT Adv. Amount R deg
VVT advance angle amount (L) VVT Adv. amount L deg
OCV duty R OCV Duty R %
OCV duty L OCV Duty L %
OCV current R OCV current R mA
OCV current L OCV Current L mA
Throttle motor duty Throttle Motor Duty %
Throttle power supply voltage Throttle Motor Voltage V
Sub throttle sensor voltage Sub-Throttle Sensor V
Main throttle sensor voltage Main-Throttle Sensor V
Sub acceleration sensor voltage Sub-Accelerator Sensor V
Main acceleration sensor voltage Main-Accelerator Sensor V
Memory vehicle speed Memorized Cruise Speed km/h
Alternate duty ratio ALT Duty %
Exhaust gas temperature signal Exhaust gas temperature°C
Estimated cumulative driving distance Odd Meter Km
Fuel level signal Fuel Level Voltage V
Intake air temperature signal Intake Air Temp.°C or °F
Mass air flow sensor signal Mass Air Flow g/s

EN(H4DOTC 2.5)-29
ENGINE (DIAGNOSTIC)
Subaru Select Monitor
NOTE:
For detailed operation procedure, refer to the “SUBARU SELECT MONITOR OPERATION MANUAL”.
Mass air flow sensor signal Air Flow Sensor Voltage V
AT/MT identification signal AT Vehicle ID Signal ON or OFF
ETC motor relay ETC Motor Relay ON or OFF
Clutch SW Clutch Switch ON or OFF
Stop Light SW Stop Light Switch ON or OFF
SET/COAST SW SET/COAST Switch ON or OFF
RESUME/ACCEL SW RESUME/ACCEL Switch ON or OFF
Brake SW Brake Switch ON or OFF
Main SW Main Switch ON or OFF
Ignition switch signal Ignition Switch ON or OFF
Test Mode Signal Test Mode Signal ON or OFF
Neutral position switch signal Neutral Position Switch ON or OFF
Air conditioning switch signal A/C Switch ON or OFF
Air conditioning signal A/C Compressor Signal ON or OFF
Radiator main fan relay signal Radiator Fan Relay #1 ON or OFF
Knocking signal Knocking Signal ON or OFF
Radiator sub fan relay signal Radiator Fan Relay #2 ON or OFF
Power steering switch signal P/S Switch ON or OFF
Rear oxygen sensor rich signalRear O
2 Rich Signal
ON or OFF
Starter switch signal Starter Switch ON or OFF
Idle switch signal Idle Switch Signal ON or OFF
Crankshaft position sensor signal Crankshaft Position Sig. ON or OFF
Camshaft position sensor signal Camshaft Position Sig. ON or OFF
Rear defogger switch signal Rear Defogger SW ON or OFF
Blower fan switch signal Blower Fan SW ON or OFF
Small light switch signal Light Switch ON or OFF
Handle switch signal Handle Switch —
Wiper switch signal Wiper Switch ON or OFF
A/C mid pressure switch signal A/C mid Pressure Switch ON or OFF
AT coordinate retard angle demand Retard Signal form AT ON or OFF
AT coordinate fuel cut demand Fuel Cut Signal from AT ON or OFF
AT coordinate permission signal Torque Permission Signal ON or OFF
UDC not torque down output Ban of Torque Down ON or OFF
UDC torque down demand Request Torque Down UDC ON or OFF
Tumble generated valve output signal TGV Output ON or OFF
Tumble generated valve drive signal TGV Drive OPEN or CLOSERemarks Display Unit of measure

EN(H4DOTC 2.5)-30
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» screen, select the {Current Data Display/Save}, and then press the [YES] key.
6) On the «Data Display Menu» screen, select the {Data Display} and press the [YES] key.
7) Using the scroll key, move 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 diagnosis code Number of Diagnosis Code —
Condition of malfunction indicator light MI (MIL) ON or OFF
Monitoring test of misfire Misfire monitoring No support
Monitoring test of fuel system Fuel system monitoring No support
Monitoring test of comprehensive component Component monitoring No support
Test of catalyst Catalyst Diagnosis No support
Test of heating-type catalyst Heated catalyst No support
Test of evaporative emission purge control system Evaporative purge system No support
Test of secondary air system Secondary air system No support
Test of air conditioning system refrigerant A/C system refrigerant No support
Test of oxygen sensor Oxygen sensor No support
Test of oxygen sensor heaterO
2 Heater Diagnosis
No support
Test of EGR system EGR system No support
Air fuel ratio control system for bank 1 Fuel System for Bank 1 —
Engine load data Calculated load value %
Engine coolant temperature signal Coolant Temp.°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 signal Mani. Absolute Pressure mmHg, kPa, inHg or psi
Engine speed signal Engine Speed rpm
Vehicle speed signal Vehicle Speed km/h or MPH
Ignition timing advance for #1 cylinder Ignition timing adv. #1°
Intake air temperature signal Intake Air Temp.°C or °F
Amount of intake air Mass Air Flow g/s
Throttle position signal Throttle Opening Angle %
Oxygen sensor #11 Oxygen Sensor #11 —
Oxygen sensor #12 Oxygen Sensor #12 —
Rear oxygen sensor output signal Oxygen Sensor #12 V
Air fuel ratio correction by rear oxygen sensor Short term fuel trim #12 %
On-board diagnostic system OBD System others
A/F sensor output signal A/F sensor #11 V
A/F lambda signal A/F sensor #11 —
A/F lambda signal #11 A/F sensor #11 —
A/F sensor current #11 A/F sensor #11 mA

EN(H4DOTC 2.5)-31
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
Diagnostic code of freeze frame data Freeze Frame Data Diagnostic code
Air fuel ratio control system for bank 1 Fuel System for Bank 1 Closed loop or open loop
Air fuel ratio control system for bank 2 Fuel System for Bank 2 —
Engine load data Calculated load valve %
Engine coolant temperature signal Coolant Temp.°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 signal Mani. Absolute Pressure mmHg, kPa, inHg or psi
Engine speed signal Engine Speed rpm
Vehicle speed signal Vehicle Speed km/h or MPH
Ignition timing advance for #1 cylinder Ignition timing adv. #1°
Intake air temperature signal Intake Air Temp.°C or °F
Amount of intake air Mass Air Flow g/s
Throttle position signal Throttle Opening Angle %

EN(H4DOTC 2.5)-32
ENGINE (DIAGNOSTIC)
Subaru Select Monitor
7. LED OPERATION MODE FOR ENGINE
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» screen, select the {Current Data Display/Save}, and then press the [YES] key.
5) On the «Data Display» screen, select the {Data & LED Display} and press the [YES] key.
6) Using the scroll key, move 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 Message LED “ON” requirements
Ignition switch signal Ignition Switch ON or OFF When ignition switch is ON.
Test Mode Signal Test Mode Signal ON or OFF When test mode connector is connected.
Neutral position switch signal Neutral Position Switch ON or OFF When neutral position signal is entered.
Air conditioning switch signal A/C Switch ON or OFF When air conditioning switch is ON.
Air conditioning relay signal A/C Compressor Signal ON or OFF When air conditioning relay is in function.
Radiator main fan relay signal Radiator Fan Relay #1 ON or OFF When radiator main fan relay is in function.
Knocking signal Knocking Signal ON or OFF When knocking signal is input.
Radiator sub fan relay signal Radiator Fan Relay #2 ON or OFF When radiator sub fan relay is in function.
Rear oxygen sensor rich signalRear O
2 Rich Signal
ON or OFFWhen rear oxygen sensor mixture ratio is
rich.
Starter switch signal Starter Switch Signal ON or OFF When starter switch signal is entered.
Idle switch signal Idle Switch Signal ON or OFF When idle switch signal is entered.
Crankshaft position sensor signal Crankshaft Position Signal ON or OFFWhen crankshaft position sensor signal is
input.
Camshaft position sensor signal Camshaft Position Signal ON or OFFWhen camshaft position sensor signal is
entered.
Power steering switch signal P/S Switch ON or OFF When power steering switch is entered.
Rear defogger switch signal Rear Defogger Switch ON or OFF When rear defogger switch is ON.
Blower fan switch signal Blower Fan Switch ON or OFF When blower fan switch is ON.
Small light switch signal Light Switch ON or OFF When small light switch is ON.
Tumble generated valve actuator
signalTGV Output ON or OFF When TGV actuator signal is entered.
Tumble generated valve drive sig-
nalTGV DriveClose or
OpenWhen TGV moves and valve opens.
Handle switch signal Handle SWLow Input
or High
InputIlluminates in Low Input.
AT/MT identification terminal AT Vehicle ID Signal ON or OFF ON (AT model).
Wiper switch signal Wiper Switch ON or OFF When wiper switch is turned to ON.
A/C mid pressure switch signal A/C Mid Pressure Switch ON or OFFWhen A/C mid pressure switch is turned to
ON.
AT coordinate retard angle
demandRetard Signal from AT ON or OFF When AT retard angle signal is exists.
AT coordinate fuel cut demand Fuel Cut Signal from AT ON or OFFWhen AT coordinate fuel cut demand signal
is exists.
AT coordinate permission signal Torque Permission Signal ON or OFFWhen AT coordinate permission signal is
exists.
VDC not torque down out put Ban of Torque Down ON or OFFWhen VDC not torque down output signal is
exists.
VDC torque down demand Request Torque Down VDC ON or OFFWhen VDC torque down demand signal is
exists.
ETC motor relay signal ETC Motor Relay ON or OFFWhen electronic throttle control relay is in
function.
Clutch switch signal Clutch Switch ON or OFF When clutch switch is ON.
Stop switch signal Stop Light Switch ON or OFF When stop light switch is ON.

EN(H4DOTC 2.5)-70
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
18.Diagnostic Procedure with Diagnostic Trouble Code (DTC)
A: DTC P0031 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Immediately at fault recognition.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode OPERATION, Clear Memory Mode.> and Inspection Mode Inspection Mode.>.
WIRING DIAGRAM:
EN-02359
SBF-5
B47 1 2 3 5 4 6
E
E
B21
E236
72
3
26
33
25
ECM
B134
1
3 2
4
B262
34 12
56
123
4
56
78
9
1011 12
1314 15 16
B21 B47 B262
B134
56 7
82 1
94 310
24 22 23 25 11 12 13 14 15
26 27
2816 17
18 19 20 21
33 34 29
32 30 31
MAIN RELAY1234BATTERY
FRONT OXYGEN
(A/F) SENSOR

EN(H4DOTC 2.5)-71
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK POWER SUPPLY TO FRONT OXY-
GEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from front oxygen
(A/F) sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between front oxygen
(A/F) sensor connector and engine ground.
Connector & terminal
(B262) No. 1 (+) — Engine ground (
−):Is the voltage more than 10 V? Go to step 2.Repair the power
supply line.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
main relay and
front oxygen (A/F)
sensor connector
 Poor contact in
front oxygen (A/F)
sensor connector
 Poor contact in
main relay connec-
tor
2 CHECK GROUND CIRCUIT FOR ECM.
Measure the resistance of harness between
ECM connector and chassis ground.
Connector & terminal
(B134) No. 6 — Chassis ground:
(B134) No. 7 — Chassis ground:Is the resistance less than 5
Ω?Go to step 3.Repair the harness
and connector.
N
OTE:
In this case repair
the following:
 Open circuit in
harness between
ECM and engine
ground cable
 Poor contact in
ECM connector.
 Poor contact in
coupling connector
3 CHECK CURRENT DATA.
1) Start the engine.
2) Read the data of front oxygen (A/F) sensor
heater current using Subaru Select Monitor or
OBD-II general scan tool.
N
OTE:
 Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. 2.5)-27, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the current more than 0.2 A? Repair poor con-
tact connector.
N
OTE:
In this case repair
the following:
 Poor contact in
front oxygen (A/F)
sensor connector
 Poor contact in
ECM connector.Go to step 4.
4 CHECK OUTPUT SIGNAL FROM ECM.
1) Start and idle the engine.
2) Measure the voltage between ECM con-
nector and chassis ground.
Connector & terminal
(B134) No. 2 (+) — Chassis ground (
−):
(B134) No. 3 (+) — Chassis ground (
−):Is the voltage less than 1 V? Go to step 6.Go to step 5.
5 CHECK OUTPUT SIGNAL FROM ECM.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B134) No. 2 (+) — Chassis ground (
−):
(B134) No. 3 (+) — Chassis ground (
−):Does the voltage change by
shaking the harness and con-
nector of ECM while monitor-
ing the value with voltage
meter?Repair the poor
contact in ECM
connector.Go to step 6.