2004 SUBARU FORESTER fuel

EN(H4SO)-72
ENGINE (DIAGNOSTIC)
List of Diagnostic Trouble Code (DTC)
18.List of Diagnostic Trouble Code (DTC)
A: LIST
DTC Item NOTE
P0030 HO2S Heater Control Circuit (Bank 1
Sensor 1) (BANK 1 SENSOR 1), Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
P0031 HO2S Heater Control Circuit Low
(Bank 1 Sensor 1) LOW (BANK 1 SENSOR 1), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P0032 HO2S Heater Control Circuit High
(Bank 1 Sensor 1) HIGH (BANK 1 SENSOR 1), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P0037 HO2S Heater Control Circuit Low
(Bank 1 Sensor 2) LOW (BANK 1 SENSOR 2), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P0038 HO2S Heater Control Circuit High
(Bank 1 Sensor 2) HIGH (BANK 1 SENSOR 2), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P0068 Manifold Pressure Sensor Range/
Pe r fo r ma nc e RANGE/PERFORMANCE, Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P0107 Manifold Absolute Pressure/Baro-
metric Pressure Circuit Low Input BAROMETRIC PRESSURE CIRCUIT LOW INPUT, Diagnostic Procedure
with Diagnostic Trouble Code (DTC).>
P0108 Manifold Absolute Pressure/Baro-
metric Pressure Circuit High Input BAROMETRIC PRESSURE CIRCUIT HIGH INPUT, Diagnostic Procedure
with Diagnostic Trouble Code (DTC).>
P0111 Intake Air Temperature Circuit
Range/Performance RANGE/PERFORMANCE, Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P0112 Intake Air Temperature Circuit Low
Input CUIT LOW INPUT, Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
P0113 Intake Air Temperature Circuit High
Input CUIT HIGH INPUT, Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
P0117 Engine Coolant Temperature Circuit
Low Input CIRCUIT LOW INPUT, Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
P0118 Engine Coolant Temperature Circuit
High Input CIRCUIT HIGH INPUT, Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
P0121 Throttle/Pedal Position Sensor/
Switch “A” Circuit Range/Perfor-
mance SOR/SWITCH “A” CIRCUIT RANGE/PERFORMANCE, Diagnostic Proce-
dure with Diagnostic Trouble Code (DTC).>
P0122 Throttle/Pedal Position Sensor/
Switch “A” Circuit Low Input SOR/SWITCH “A” CIRCUIT LOW INPUT, Diagnostic Procedure with Diag-
nostic Trouble Code (DTC).>
P0123 Throttle/Pedal Position Sensor/
Switch “A” Circuit High Input SOR/SWITCH “A” CIRCUIT HIGH INPUT, Diagnostic Procedure with Diag-
nostic Trouble Code (DTC).>
P0125 Insufficient Coolant Temperature For
Closed Loop Fuel Control ATURE FOR CLOSED LOOP FUEL CONTROL, Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>
P0129 Barometric Pressure Too Low LOW, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>

EN(H4SO)-74
ENGINE (DIAGNOSTIC)
List of Diagnostic Trouble Code (DTC)
P0420 Catalyst System Efficiency Below
Threshold (Bank 1) BELOW THRESHOLD (BANK 1), Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
P0458 Evaporative Emission Control Sys-
tem Purge Control Valve Circuit Low TROL SYSTEM PURGE CONTROL VALVE CIRCUIT LOW, Diagnostic Pro-
cedure with Diagnostic Trouble Code (DTC).>
P0459 Evaporative Emission Control Sys-
tem Purge Control Valve Circuit High TROL SYSTEM PURGE CONTROL VALVE CIRCUIT HIGH, Diagnostic
Procedure with Diagnostic Trouble Code (DTC).>
P0461 Fuel Level Sensor Circuit Range/Per-
formance RANGE/PERFORMANCE, Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P0462 Fuel Level Sensor Circuit Low Input INPUT, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0463 Fuel Level Sensor Circuit High Input HIGH INPUT, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0464 Fuel Level Sensor Circuit Intermittent INTERMITTENT, Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
P0483 Cooling Fan Rationality Check CHECK, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0502 Vehicle Speed Sensor Circuit Low
Input LOW INPUT, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0503 Vehicle Speed Sensor Intermittent/
Erratic/High HIGH INPUT, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0506 Idle Control System RPM Lower
Than Expected LOWER THAN EXPECTED, Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P0507 Idle Control System RPM Higher
Than Expected HIGHER THAN EXPECTED, Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P0512 Starter Request Circuit nostic Procedure with Diagnostic Trouble Code (DTC).>
P0513 Incorrect Immobilizer Key Procedure with Diagnostic Trouble Code (DTC).>
P0519 Idle Control System Malfunction
(Fail-Safe) TION (FAIL-SAFE), Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
P0565 Cruise Control On Signal Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0604 Internal Control Module Random
Access Memory (RAM) Error READ ACCESS MEMORY (RAM) ERROR, Diagnostic Procedure with Diag-
nostic Trouble Code (DTC).>
P0691 Cooling Fan 1 Control Circuit Low LOW, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0692 Cooling Fan 1 Control Circuit High HIGH, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0703 Torque Converter/Brake Switch “B”
Circuit SWITCH “B” CIRCUIT, Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
P0705 Transmission Range Sensor Circuit
(PRNDL Input) dure without Diagnostic Trouble Code (DTC).>
P0710 Transmission Fluid Temperature
Sensor Circuit tic Procedure with Diagnostic Trouble Code (DTC).>
P0716 Torque converter turbine speed sen-
sor SENSOR, Diagnostic Procedure with Diagnostic Trouble Code (DTC).> DTC Item NOTE

EN(H4SO)-82
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
7 CHECK FRONT OXYGEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Measure the resistance between front oxy-
gen (A/F) sensor connector terminals.
Te r m i n a l s
No. 3 — No. 4:Is the resistance less than 10
Ω?Repair harness
and connector.
N
OTE:
In this case repair
the following:
 Open or ground
short circuit in har-
ness between front
oxygen (A/F)
sensor and ECM
connector
 Poor contact in
front oxygen (A/F)
sensor connector
 Poor contact in
ECM connector.Replace the front
oxygen (A/F) sen-
sor. FU(H4SO)-47,
Fuel.> Step Check Yes No

EN(H4SO)-117
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Q: DTC P0125 INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP
FUEL CONTROL
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
Engine would not return to idling.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode tion Mode.>.
WIRING DIAGRAM:
EN-02388
1
2
B122
1912
913
B135ECM
21
E3
B22
E8 ENGINE
COOLANT
TEMPERATURE
SENSOR
E8
12
3
B135
567
82 1
94
310
24 22 23 251112131415
26 27
281617181920 21
B22
125678
131415169101112
34
17181920
B122 : LHD
12345678
B122 : RHD
1234

EN(H4SO)-121
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Inspect the DTC
using “List of Diag-
nostic Trouble
Code (DTC)”.
EN(H4SO)-72, List
of Diagnostic Trou-
ble Code (DTC).>Go to step 2.
2 CHECK FRONT (A/F) OXYGEN SENSOR DA-
TA.
1) Start the engine.
2) While observing the Subaru Select Monitor
or OBD-II general scan tool screen, warm-up
the engine until coolant temperature is above
70°C (160°F).
If the engine is already warmed-up, operate at
idle speed for at least 1 minute.
3) Read the data of front oxygen (A/F) sensor
signal using Subaru Select Monitor or OBD-II
general scan tool.
NOTE:
 Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. to EN(H4SO)-29, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the voltage 0.85 — 1.15 V? Go to step 3.Go to step 4.
3 CHECK FRONT (A/F) OXYGEN SENSOR DA-
TA.
1) Race the engine at speeds from idling to
5,000 rpm for a total of 5 cycles.
2) Read the data of front oxygen (A/F) sensor
signal at racing using Subaru Select Monitor or
OBD-II general scan tool.
N
OTE:
 Normally the air fuel ratio be rich at racing.
 To increase engine speed to 5,000 rpm,
slowly depress accelerator pedal, taking
approximately 5 seconds, and quickly release
accelerator pedal to decrease engine speed.Is the voltage more than 1.1 V? Go to step 6.Go to step 4.
4 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from ECM and
front oxygen (A/F) sensor connector.
3) Measure the resistance between ECM and
front oxygen (A/F) sensor.
Connector & terminal
(B136) No. 13 — (B18) No. 1:
(B136) No. 22 — (B18) No. 2:Is the resistance less than 5
Ω?Go to step 5.Repair open circuit
between ECM and
front oxygen (A/F)
sensor.
5 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR.
Measure the resistance between ECM and
chassis ground.
Connector & terminal
(B136) No. 13 — Chassis ground:
(B136) No. 22 — Chassis ground:Is the resistance more than 1
MΩ?Go to step 6.Repair ground
short circuit
between ECM and
front oxygen (A/F)
sensor.

EN(H4SO)-139
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AB:DTC P0172 SYSTEM TOO RICH (BANK 1)
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
TROUBLE SYMPTOM:
 Erroneous idling
 Engine stalls.
 Poor driving performance
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode tion Mode.>.
Step Check Yes No
1 CHECK EXHAUST SYSTEM.Are there holes or loose bolts
on exhaust system?Repair exhaust
system.Go to step 2.
2 CHECK EGR VALVE.Is the EGR valve stuck? Replace the EGR
valve.Go to step 3.
3 CHECK AIR INTAKE SYSTEM.Are there holes, loose bolts or
disconnection of hose on air
intake system?Repair air intake
system.Go to step 4.
4 CHECK PURGE CONTROL SOLENOID
VALVE.Is the purge control solenoid
valve stuck?Replace the purge
control solenoid
valve.Go to step 5.
5 CHECK PCV VALVE.Is the PCV valve stuck? Replace the PCV
valve.Go to step 6.
6 CHECK FUEL PRESSURE.
Warning:
 Place “NO FIRE” signs near the working
area.
 Be careful not to spill fuel.
1) Release the fuel pressure.
(1) Disconnect the connector from fuel
pump relay.
(2) Start the engine and run it until it stalls.
(3) After the engine stalls, crank it for five
more seconds.
(4) Turn the ignition switch to OFF.
2) Connect the connector to fuel pump relay.
3) Disconnect the fuel delivery hose, and con-
nect the fuel pressure gauge.
4) Install the fuel filler cap.
5) Start the engine and idle while gear posi-
tion is neutral.
6) Measure the fuel pressure while discon-
necting pressure regulator vacuum hose from
intake manifold.
Warning:
Release fuel pressure before removing the
fuel pressure gauge.
NOTE:
If fuel pressure does not increase, squeeze fuel
return hose 2 to 3 times, then measure fuel
pressure again.Is measured value 284 — 314
kPa (2.9 — 3.2 kg/cm
2, 41 —
46 psi)?Go to step 7.Repair the follow-
ing items.
Fuel pressure is
too high:
 Clogged fuel
return line or
bent hose
Fuel pressure is
too low:
 Improper fuel
pump discharge
 Clogged fuel
supply line

EN(H4SO)-140
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
7 CHECK FUEL PRESSURE.
After connecting the pressure regulator vac-
uum hose, measure fuel pressure.
Warning:
Release fuel pressure before removing the
fuel pressure gauge.
N
OTE:
 If fuel pressure does not increase, squeeze
fuel return hose 2 to 3 times, then measure
fuel pressure again.
 If out of specification as measured at this
step, check or replace pressure regulator and
pressure regulator vacuum hose.Is measured value 206 — 235
kPa (2.1 — 2.4 kg/cm
2, 30 —
34 psi)?Go to step 8.Repair the follow-
ing items.
Fuel pressure is
too high:
 Faulty pres-
sure regulator
 Clogged fuel
return line or
bent hose
Fuel pressure is
too low:
 Faulty pres-
sure regulator
 Improper fuel
pump discharge
 Clogged fuel
supply line
8 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Start the engine and warm-up completely.
2) Read the data of engine coolant tempera-
ture sensor signal using Subaru Select Monitor
or the OBD-II scan tool.
NOTE:
 Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. to EN(H4SO)-29, Subaru Select Monitor.>
 OBD-II scan tool
For detailed operation procedures, refer to the
OBD-II Scan Tool Instruction Manual.Is the engine coolant tempera-
ture 70 — 100°C (158 —
212°F)?Go to step 9.Replace the
engine coolant
temperature sen-
sor. FU(H4SO)-25,
Engine Coolant
Temperature Sen-
sor.>
9 CHECK MANIFOLD PRESSURE SENSOR
SIGNAL.
1) Start and warm-up the engine until engine
coolant temperature is greater than 60°C
(140°F).
2) Shift the select lever to “N” or “P” range.
3) Turn the A/C switch to OFF.
4) Turn all accessory switches to OFF.
5) Read the data of manifold absolute pres-
sure sensor signal using Subaru Select Moni-
tor or OBD-II scan tool.
NOTE:
 Subaru Select Monitor
For detailed operation procedure, refer to the
“READ CURRENT DATA FOR ENGINE”. to EN(H4SO)-29, Subaru Select Monitor.>
 OBD-II scan tool
For detailed operation procedures, refer to the
OBD-II Scan Tool Instruction Manual.Is the measurement value at
idling: 24.0 — 41.3 kPa (180 —
310 mmHg, 7.09 — 12.20
inHg), at ignition ON: 73.3 —
106.6 kPa (550 — 800 mmHg,
21.65 — 31.50 inHg)?Contact the SUB-
ARU dealer.
NOTE:
Inspection by DTM
is required,
because probable
cause is deteriora-
tion of multiple
parts.Replace the mani-
fold absolute pres-
sure sensor. to FU(H4SO)-31,
Manifold Absolute
Pressure Sensor.> Step Check Yes No

EN(H4SO)-142
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AF:DTC P0304 CYLINDER 4 MISFIRE DETECTED
DTC DETECTING CONDITION:
 Two consecutive driving cycles with fault
 Immediately at fault recognition (A misfire which could damage catalyst occurs.)
TROUBLE SYMPTOM:
 Engine stalls
 Erroneous idling
 Rough driving
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode ERATION, Clear Memory Mode.> and Inspection Mode tion Mode.>.
WIRING DIAGRAM:
EN-02383
B21
12345678910111213141516
E6E17
E5E16
12
12121212
2223348
91101112
ECM
B134
E5E16E6E17
B21
E2
FUEL INJECTOR
No. 1FUEL INJECTOR
No. 2FUEL INJECTOR
No. 3FUEL INJECTOR
No. 4
BATTERY
F44B61
SBF-5
B47 MAIN RELAY
12
35
46
B47
34
12
56
F44
12345678
B134
1234567891011121314151617181920212223242526272829303132333435
LHDLHD
RHDRHD
7