engine SUBARU FORESTER 2004 Service Repair Manual

EN(H4DOTC)-77
ENGINE (DIAGNOSTIC)
List of Diagnostic Trouble Code (DTC)
P0507 Idle Control System RPM Higher
Than Expected<Ref. to EN(H4DOTC)-211, DTC P0507 IDLE CONTROL SYSTEM RPM
HIGHER THAN EXPECTED, Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P0508 Idle Control System Circuit Low <Ref. to EN(H4DOTC)-213, DTC P0508 IDLE CONTROL SYSTEM CIR-
CUIT LOW, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0509 Idle Control System Circuit High <Ref. to EN(H4DOTC)-215, DTC P0509 IDLE CONTROL SYSTEM CIR-
CUIT HIGH, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0512 Starter Request Circuit <Ref. to EN(H4DOTC)-217, DTC P0512 STARTER REQUEST CIRCUIT,
Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0513 Incorrect Immobilizer Key <Ref. to IM-20, DTC P0513 INCORRECT IMMOBILIZER KEY, Diagnostics
Procedure with Diagnostic Trouble Code (DTC).>
P0519 Idle Control System Malfunction
(Fail-Safe)<Ref. to EN(H4DOTC)-219, DTC P0519 IDLE CONTROL SYSTEM MAL-
FUNCTION (FAIL-SAFE), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P0545 Exhaust Gas Temperature Sensor
Circuit Low - Bank 1<Ref. to EN(H4DOTC)-221, DTC P0545 EXHAUST GAS TEMPERATURE
SENSOR CIRCUIT LOW - BANK 1, Diagnostic Procedure with Diagnostic
Trouble Code (DTC).>
P0546 Exhaust Gas Temperature Sensor
Circuit High - Bank 1<Ref. to EN(H4DOTC)-223, DTC P0546 EXHAUST GAS TEMPERATURE
SENSOR HIGH - BANK 1, Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P0558 Generator Circuit Low Input <Ref. to EN(H4DOTC)-225, DTC P0558 GENERATOR CIRCUIT LOW
INPUT, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0559 Generator Circuit High Input <Ref. to EN(H4DOTC)-226, DTC P0559 GENERATOR CIRCUIT HIGH
INPUT, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0600 Serial Communication Link <Ref. to EN(H4DOTC)-228, DTC P0600 SERIAL COMMUNICATION LINK,
Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0604 Internal Control Module Random
Access Memory (RAM) Error<Ref. to EN(H4DOTC)-230, DTC P0604 INTERNAL CONTROL MODULE
READ ONLY MEMORY (ROM) ERROR, Diagnostic Procedure with Diag-
nostic Trouble Code (DTC).>
P0691 Cooling Fan 1 Control Circuit Low <Ref. to EN(H4DOTC)-232, DTC P0691 COOLING FAN 1 CONTROL CIR-
CUIT LOW, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0692 Cooling Fan 1 Control Circuit High <Ref. to EN(H4DOTC)-236, DTC P0692 COOLING FAN 1 CONTROL CIR-
CUIT HIGH, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P0700 Transmission Control System (MIL
Request)<Ref. to EN(H4DOTC)-238, DTC P0700 TRANSMISSION CONTROL SYS-
TEM (MIL REQUEST), Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
P0851 Neutral Switch Input Circuit Low <Ref. to EN(H4DOTC)-239, DTC P0851 NEUTRAL SWITCH INPUT CIR-
CUIT LOW (AT MODEL), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).> or <Ref. to EN(H4DOTC)-241, DTC P0851 NEUTRAL
SWITCH INPUT CIRCUIT LOW (MT MODEL), Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>
P0852 Neutral Switch Input Circuit High <Ref. to EN(H4DOTC)-243, DTC P0852 NEUTRAL SWITCH INPUT CIR-
CUIT HIGH (AT MODEL), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).> or <Ref. to EN(H4DOTC)-246, DTC P0852 NEUTRAL
SWITCH INPUT CIRCUIT HIGH (MT MODEL), Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>
P1086 Tumble Generated Valve Position
Sensor 2 Circuit Low<Ref. to EN(H4DOTC)-248, DTC P1086 TUMBLE GENERATED VALVE
POSITION SENSOR 2 CIRCUIT LOW, Diagnostic Procedure with Diagnos-
tic Trouble Code (DTC).>
P1087 Tumble Generated Valve Position
Sensor 2 Circuit High<Ref. to EN(H4DOTC)-252, DTC P1087 TUMBLE GENERATED VALVE
POSITION SENSOR 2 CIRCUIT HIGH, Diagnostic Procedure with Diagnos-
tic Trouble Code (DTC).>
P1088 Tumble Generated Valve Position
Sensor 1 Circuit Low<Ref. to EN(H4DOTC)-255, DTC P1088 TUMBLE GENERATED VALVE
POSITION SENSOR 1 CIRCUIT LOW, Diagnostic Procedure with Diagnos-
tic Trouble Code (DTC).> DTC Item NOTE

EN(H4DOTC)-78
ENGINE (DIAGNOSTIC)
List of Diagnostic Trouble Code (DTC)
P1089 Tumble Generated Valve Position
Sensor 1 Circuit High<Ref. to EN(H4DOTC)-259, DTC P1089 TUMBLE GENERATED VALVE
POSITION SENSOR 1 CIRCUIT HIGH, Diagnostic Procedure with Diagnos-
tic Trouble Code (DTC).>
P1090 Tumble Generated Valve System 1
(Valve Open)<Ref. to EN(H4DOTC)-262, DTC P1090 TUMBLE GENERATED VALVE
SYSTEM 1 (VALVE OPEN), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P1091 Tumble Generated Valve System 1
(Valve Close)<Ref. to EN(H4DOTC)-262, DTC P1091 TUMBLE GENERATED VALVE
SYSTEM 1 (VALVE CLOSE), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P1092 Tumble Generated Valve System 2
(Valve Open)<Ref. to EN(H4DOTC)-263, DTC P1092 TUMBLE GENERATED VALVE
SYSTEM 2 (VALVE OPEN), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P1093 Tumble Generated Valve System 2
(Valve Close)<Ref. to EN(H4DOTC)-263, DTC P1093 TUMBLE GENERATED VALVE
SYSTEM 2 (VALVE CLOSE), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P1094 Tumble Generated Valve Signal 1
Circuit Malfunction (Open)<Ref. to EN(H4DOTC)-264, DTC P1094 TUMBLE GENERATED VALVE
SIGNAL 1 CIRCUIT MALFUNCTION (OPEN), Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>
P1095 Tumble Generated Valve Signal 1
Circuit Malfunction (Short)<Ref. to EN(H4DOTC)-266, DTC P1095 TUMBLE GENERATED VALVE
SIGNAL 1 CIRCUIT MALFUNCTION (SHORT), Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>
P1096 Tumble Generated Valve Signal 2
Circuit Malfunction (Open)<Ref. to EN(H4DOTC)-268, DTC P1096 TUMBLE GENERATED VALVE
SIGNAL 2 CIRCUIT MALFUNCTION (OPEN), Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>
P1097 Tumble Generated Valve Signal 2
Circuit Malfunction (Short)<Ref. to EN(H4DOTC)-270, DTC P1097 TUMBLE GENERATED VALVE
SIGNAL 2 CIRCUIT MALFUNCTION (SHORT), Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>
P1110 Atmospheric Pressure Sensor Cir-
cuit Malfunction (Low Input)<Ref. to EN(H4DOTC)-271, DTC P1110 ATMOSPHERIC PRESSURE SEN-
SOR CIRCUIT MALFUNCTION (LOW INPUT), Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>
P1111 Atmospheric Pressure Sensor Cir-
cuit Malfunction (High Input)<Ref. to EN(H4DOTC)-271, DTC P1111 ATMOSPHERIC PRESSURE SEN-
SOR CIRCUIT MALFUNCTION (HIGH INPUT), Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>
P1152 O
2 Sensor Circuit Range/Perfor-
mance (Low) (Bank 1 Sensor 1)<Ref. to EN(H4DOTC)-272, DTC P1152 O2 SENSOR CIRCUIT RANGE/
PERFORMANCE (LOW) (BANK 1 SENSOR 1), Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>
P1153 O
2 Sensor Circuit Range/Perfor-
mance (High) (Bank 1 Sensor 1)<Ref. to EN(H4DOTC)-274, DTC P1153 O2 SENSOR CIRCUIT RANGE/
PERFORMANCE (HIGH) (BANK 1 SENSOR 1), Diagnostic Procedure with
Diagnostic Trouble Code (DTC).>
P1301 Misfire Detected (High Tempera-
ture Exhaust Gas)<Ref. to EN(H4DOTC)-276, DTC P1301 MISFIRE DETECTED (HIGH TEM-
PERATURE EXHAUST GAS), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P1312 Exhaust Gas Temperature Sensor
Malfunction<Ref. to EN(H4DOTC)-278, DTC P1312 INTAKE AIR TEMPERATURE CIR-
CUIT RANGE/PERFORMANCE, Diagnostic Procedure with Diagnostic Trou-
ble Code (DTC).>
P1518 Starter Switch Circuit Low Input <Ref. to EN(H4DOTC)-280, DTC P1518 STARTER SWITCH CIRCUIT LOW
INPUT, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P1544 Exhaust Gas Temperature Too
High<Ref. to EN(H4DOTC)-282, DTC P1544 EXHAUST GAS TEMPERATURE
TOO HIGH, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>
P1560 Back-Up Voltage Circuit Malfunc-
tion<Ref. to EN(H4DOTC)-284, DTC P1560 BACK-UP VOLTAGE CIRCUIT
MALFUNCTION, Diagnostic Procedure with Diagnostic Trouble Code
(DTC).>
P1570 ANTENNA <Ref. to IM-21, DTC P1570 ANTENNA, Diagnostics Procedure with Diag-
nostic Trouble Code (DTC).>
P1571 Reference Code Incompatibility <Ref. to IM-15, DTC P1571 REFERENCE CODE INCOMPATIBILITY, Diag-
nostics Procedure with Diagnostic Trouble Code (DTC).> DTC Item NOTE

EN(H4DOTC)-79
ENGINE (DIAGNOSTIC)
List of Diagnostic Trouble Code (DTC)
P1572 IMM Circuit Failure (Except
Antenna Circuit)<Ref. to IM-19, DTC P1574 KEY COMMUNICATION FAILURE, Diagnostics
Procedure with Diagnostic Trouble Code (DTC).>
P1574 Key Communication Failure <Ref. to IM-19, DTC P1574 KEY COMMUNICATION FAILURE, Diagnostics
Procedure with Diagnostic Trouble Code (DTC).>
P1576 EGI Control Module EEPROM <Ref. to IM-20, DTC P1576 EGI CONTROL MODULE EEPROM, Diagnos-
tics Procedure with Diagnostic Trouble Code (DTC).>
P1577 IMM Control Module EEPROM <Ref. to IM-20, DTC P1577 IMM CONTROL MODULE EEPROM, Diagnos-
tics Procedure with Diagnostic Trouble Code (DTC).>
P2088 OCV Solenoid Valve Signal A Cir-
cuit Open (Bank 1)<Ref. to EN(H4DOTC)-287, DTC P2088 OCV SOLENOID VALVE SIGNAL A
CIRCUIT OPEN (BANK 1), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P2089 OCV Solenoid Valve Signal A Cir-
cuit Short (Bank 1)<Ref. to EN(H4DOTC)-289, DTC P2089 OCV SOLENOID VALVE SIGNAL A
CIRCUIT SHORT (BANK 1), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P2092 OCV Solenoid Valve Signal A Cir-
cuit Open (Bank 2)<Ref. to EN(H4DOTC)-291, DTC P2092 OCV SOLENOID VALVE SIGNAL A
CIRCUIT OPEN (BANK 2), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).>
P2093 OCV Solenoid Valve Signal A Cir-
cuit Short (Bank 2)<Ref. to EN(H4DOTC)-293, DTC P2093 OCV SOLENOID VALVE SIGNAL A
CIRCUIT SHORT (BANK 2), Diagnostic Procedure with Diagnostic Trouble
Code (DTC).> DTC Item NOTE

FUJI HEAVY INDUSTRIES LTD. G8080GE3
2004 FORESTER 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 SYSTEM) FU(H4DOTC)
EMISSION CONTROL
(AUX. EMISSION CONTROL DEVICE)EC(H4DOTC)
INTAKE (INDUCTION) IN(H4DOTC)
MECHANICAL ME(H4DOTC)
EXHAUST EX(H4DOTC)
COOLING CO(H4DOTC)
LUBRICATION LU(H4DOTC)
SPEED CONTROL SYSTEM SP(H4DOTC)
IGNITION IG(H4DOTC)
STARTING/CHARGING SYSTEM SC(H4DOTC)
ENGINE (DIAGNOSTIC) EN(H4DOTC)

ENGINE (DIAGNOSTIC)
EN(H4DOTC)
Page
1. Basic Diagnostics Procedure ......................................................................2
2. Check List for Interview ...............................................................................4
3. General Description ....................................................................................6
4. Electrical Component Location ...................................................................9
5. Engine Control Module (ECM) I/O Signal .................................................23
6. Engine Condition Data ..............................................................................27
7. Transmission Control Module (TCM) I/O Signal .......................................28
8. Data Link Connector .................................................................................29
9. OBD-II General Scan Tool ........................................................................30
10. Subaru Select Monitor...............................................................................33
11. Read Diagnostic Trouble Code (DTC) ......................................................39
12. Inspection Mode ........................................................................................40
13. Drive Cycle ................................................................................................45
14. Clear Memory Mode..................................................................................47
15. Compulsory Valve Operation Check Mode ...............................................48
16. Malfunction Indicator Light ........................................................................50
17. Diagnostics for Engine Starting Failure .....................................................59
18. List of Diagnostic Trouble Code (DTC) .....................................................74
19. Diagnostic Procedure with Diagnostic Trouble Code (DTC) .....................80
20. General Diagnostic Table........................................................................295

EN(H4DOTC)-80
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
19.Diagnostic Procedure with Diagnostic Trouble Code (DTC)
A: DTC P0011 “A” CAMSHAFT POSITION - TIMING OVER - ADVANCED OR
SYSTEM PERFORMANCE (BANK 1)
DTC DETECTING CONDITION:
Detect as soon as the malfunction occurs.
TROUBLE SYMPTOM:
 Engine stalls.
 Erroneous idling
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)-47, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)-40, Inspection Mode.>.
Step Check Yes No
1 CHECK DTC ON DISPLAY.Is any other DTC displayed? Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H4DOTC)-74,
List of Diagnostic
Trouble Code
(DTC).>Go to step 2.
2 CHECK CURRENT DATA.
1) Start the engine and idle it.
2) Check the AVCS system operating angle
and oil flow control solenoid valve duty output
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”. <Ref. to EN(H4DOTC)-
33, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the AVCS system operating
angle approx. 0 degree and oil
flow control solenoid valve duty
output approx. 10%?A temporary poor
malfunction. Per-
for m the following
to clean oil routing.
Replace the
engine oil, and
then idle the
engine for 5 min-
utes and replace
the oil filter and
engine oil.Check the follow-
ing and repair or
replace it if neces-
sary.
 Oil pipe (clog-
ging)
 Oil flow con-
trol solenoid
valve (clogging
or dirt of oil
routing, spring
setting, clog-
ging of valve)
 Intake cam-
shaft (dirt, dam-
age of
camshaft)
 Timing belt
(alignment of
timing mark)

EN(H4DOTC)-81
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
B: DTC P0021 “A” CAMSHAFT POSITION - TIMING OVER - ADVANCED OR
SYSTEM PERFORMANCE (BANK 2)
DTC DETECTING CONDITION:
Detect as soon as the malfunction occurs.
TROUBLE SYMPTOM:
 Engine stalls.
 Erroneous idling
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)-47, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)-40, Inspection Mode.>.
Step Check Yes No
1 CHECK DTC ON DISPLAY.Is any other DTC displayed? Inspect the rele-
vant DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H4DOTC)-74,
List of Diagnostic
Trouble Code
(DTC).>Go to step 2.
2 CHECK CURRENT DATA.
1) Start the engine and idle it.
2) Check the AVCS system operating angle
and oil flow control solenoid valve duty output
using Subaru Select Monitor or OBD-II general
scan tool.
NOTE:
 Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA SHOWN ON DIS-
PLAY FOR ENGINE”. <Ref. to EN(H4DOTC)-
33, Subaru Select Monitor.>
 OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Operation Manual.Is the AVCS system operating
angle approx. 0 degree and oil
flow control solenoid valve duty
output approx. 10%?A temporary poor
malfunction. Per-
for m the following
to clean oil routing.
Replace the
engine oil, and
then idle the
engine for 5 min-
utes and replace
the oil filter and
engine oil.Check the follow-
ing and repair or
replace it if neces-
sary.
 Engine oil
(amount, dirt)
 Oil pipe (clog-
ging)
 Oil flow con-
trol solenoid
valve (clogging
or dirt of oil
routing, spring
setting, clog-
ging of valve)
 Intake cam-
shaft (dirt, dam-
age of
camshaft)
 Timing belt
(alignment of
timing mark)

EN(H4DOTC)-82
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
C: DTC P0031 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Two consecutive driving cycles with fault
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)-47, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)-40, Inspection Mode.>.
WIRING DIAGRAM:
EN-02320
BATTERYMAIN RELAYSBF-5
B47 1 2 3 5 4 6
E
E
B100F2
14LHD
RHD
LHD
RHD
B100
F2
F60
E3
20
3
RHD
RHD6
72
3
33
26
25
ECMB134
: LHD: LHD
B21: RHD: RHD
1
4 2
3
B262
FRONT OXYGEN
(A/F) SENSOR
3412
56
123
4
56
78
9
1011 12
1314 15 16
B21
F60
B47
B262
B134
F2
LHD LHD
1234
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
1234 5678910 11 12 13 14 15 16 17 18 19 20
: LHDE2: RHD

EN(H4DOTC)-83
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step Check Yes No
1 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
1) Start the engine, and warm-up the engine.
2) Turn the ignition switch to OFF.
3) Disconnect the connector from ECM and
front oxygen (A/F) sensor.
4) Measure the resistance of harness
between ECM and front oxygen (A/F) sensor
connector.
Connector & terminal
(B134)No. 2 — (B262)No. 2:
(B134)No. 3 — (B262)No. 2:Is the resistance less than 1
Ω?Go to step 2.Repair the open
circuit in harness
between ECM and
front oxygen (A/F)
sensor connector.
2 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure the resistance of harness between
ECM and front oxygen (A/F) sensor connector.
Connector & terminal
(B134) No. 33 — (B262) No. 4:
(B134) No. 26 — (B262) No. 3:Is the resistance less than 1
Ω?Go to step 3.Repair the open
circuit in harness
between ECM and
front oxygen (A/F)
sensor connector.
3 CHECK HARNESS BETWEEN ECM AND
FRONT OXYGEN (A/F) SENSOR CONNEC-
TOR.
Measure the resistance of harness between
main relay and front oxygen (A/F) sensor con-
nector.
Connector & terminal
(B47) No. 4 — (B262) No. 1:Is the resistance less than 1
Ω?Go to step 4.Repair the open
circuit in harness
between ECM and
front oxygen (A/F)
sensor connector.
4 CHECK FRONT OXYGEN (A/F) SENSOR.
Measure the resistance between front oxygen
(A/F) sensor connector terminals.
Te r m i n a l s
No. 2 — No. 1:Is the resistance less than 5
Ω?Go to step 5.Replace the front
oxygen (A/F) sen-
sor. <Ref. to
FU(H4DOTC)-45,
Front Oxygen (A/
F) Sensor.>
5 CHECK POOR CONTACT.
Check poor contact in ECM and front oxygen
(A/F) sensor connector. Is there poor contact in ECM or
front oxygen (A/F) sensor con-
nector?Repair the poor
contact in ECM
and front oxygen
(A/F) sensor.Replace the front
oxygen (A/F) sen-
sor. <Ref. to
FU(H4DOTC)-45,
Front Oxygen (A/
F) Sensor.>

EN(H4DOTC)-84
ENGINE (DIAGNOSTIC)
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
D: DTC P0031 HO2S HEATER CONTROL CIRCUIT LOW (BANK 1 SENSOR 1)
DTC DETECTING CONDITION:
Detect as soon as the malfunction occurs.
CAUTION:
After repair or replacement of faulty parts, conduct Clear Memory Mode <Ref. to EN(H4DOTC)-47, OP-
ERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4DOTC)-40, Inspection Mode.>.
WIRING DIAGRAM:
EN-02320
BATTERYMAIN RELAYSBF-5
B47 1 2 3 5 4 6
E
E
B100F2
14LHD
RHD
LHD
RHD
B100
F2
F60
E3
20
3
RHD
RHD6
72
3
33
26
25
ECMB134
: LHD: LHD
B21: RHD: RHD
1
4 2
3
B262
FRONT OXYGEN
(A/F) SENSOR
3412
56
123
4
56
78
9
1011 12
1314 15 16
B21
F60
B47
B262
B134
F2
LHD LHD
1234
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
1234 5678910 11 12 13 14 15 16 17 18 19 20
: LHDE2: RHD