SUBARU LEGACY 1996 Service Repair Manual

10. Diagnostics Chart with Trouble
Code
A: DIAGNOSTIC TROUBLE CODE (DTC) LIST
DTC
No.Abbreviation
(Subaru select monitor)Item Page
P0100 QA Mass air flow sensor circuit malfunction 125
P0101 QA
—R Mass air flow sensor circuit range/performance problem 132
P0105 P
—S Pressure sensor circuit malfunction 134
P0106 PS
—R Pressure sensor circuit range/performance problem 142
P0115 TW Engine coolant temperature sensor circuit malfunction 147
P0120 THV Throttle position sensor circuit malfunction 151
P0121 TH
—R Throttle position sensor circuit range/performance problem 157
P0125 TW
—CL Insufficient coolant temperature for closed loop fuel control 159
P0130 FO2
—V Front oxygen sensor circuit malfunction 161
P0133 FO2
—R Front oxygen sensor circuit slow response 164
P0135 FO2H Front oxygen sensor heater circuit malfunction 166
P0136 RO2
—V Rear oxygen sensor circuit malfunction 172
P0139 RO2
—R Rear oxygen sensor circuit slow response 177
P0141 RO2H Rear oxygen sensor heater circuit malfunction 179
P0170 FUEL Fuel trim malfunction 185
P0180 TNKT Fuel temperature sensor A circuit malfunction 190
P0181 TNKT
—F Fuel temperature sensor A circuit range/performance problem 195
P0201 INJ1 Fuel injector circuit malfunction - #1
197 P0202 INJ2 Fuel injector circuit malfunction - #2
P0203 INJ3 Fuel injector circuit malfunction - #3
P0204 INJ4 Fuel injector circuit malfunction - #4
P0301 MIS
—1 Cylinder 1 misfire detected
203 P0302 MIS
—2 Cylinder 2 misfire detected
P0303 MIS
—3 Cylinder 3 misfire detected
P0304 MIS
—4 Cylinder 4 misfire detected
P0325 KNOCK Knock sensor circuit malfunction 211
P0335 CRANK Crankshaft position sensor circuit malfunction 215
P0340 CAM Camshaft position sensor circuit malfunction 218
P0400 EGR Exhaust gas recirculation flow malfunction 221
P0403 EGRSOL Exhaust gas recirculation circuit malfunction 227
P0420 CAT Catalyst system efficiency below threshold 233
P0440 EVAP Evaporative emission control system malfunction 236
P0441 CPC
—F Evaporative emission control system incorrect purge flow 241
P0443 CPC Evaporative emission control system purge control valve circuit malfunction 244
P0446 VCMSOL Evaporative emission control system vent control malfunction 249
P0450 TNKP Evaporative emission control system pressure sensor malfunction 255
P0451 TNKP
—F Evaporative emission control system pressure sensor range/performance problem 264
123
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

DTC
No.Abbreviation
(Subaru select monitor)Item Page
P0500 VSP Vehicle speed sensor malfunction 266
P0505 ISC Idle control system malfunction 269
P0506 ISC
—L Idle control system RPM lower than expected 276
P0507 ISC
—H Idle control system RPM higher than expected 277
P0600—Serial communication link malfunction 278
P0601 RAM Internal control module memory check sum error 281
P0703 ATBRK Brake switch input malfunction 283
P0705 ATRNG Transmission range sensor circuit malfunction 286
P0710 ATF Transmission fluid temperature sensor circuit malfunction 293
P0720 ATVSP Output speed sensor (vehicle speed sensor 1) circuit malfunction 294
P0725 ATNE Engine speed input circuit malfunction 295
P0731 ATGR1 Gear 1 incorrect ratio
296 P0732 ATGR2 Gear 2 incorrect ratio
P0733 ATGR3 Gear 3 incorrect ratio
P0734 ATGR4 Gear 4 incorrect ratio
P0740 ATLU
—F Torque converter clutch system malfunction 300
P0743 ATLU Torque converter clutch system electrical 304
P0748 ATPL Pressure control solenoid electrical 305
P0753 ATSFT1 Shift solenoid A electrical 306
P0758 ATSFT2 Shift solenoid B electrical 307
P0760 ATOVR
—F Shift solenoid C malfunction 308
P0763 ATOVR Shift solenoid C electrical 312
P1100 ST
—SW Starter switch circuit malfunction 313
P1101 N/P
—SW Neutral position switch circuit malfunction [MT vehicles] 315
P1101 N/P
—SW Neutral position switch circuit malfunction [AT vehicles] 318
P1102 BR Pressure sources switching solenoid valve circuit malfunction 322
P1103 TRQ Engine torque control signal circuit malfunction 328
P1400 PCVSOL Fuel tank pressure control solenoid valve circuit malfunction 331
P1401 PCV
—F Fuel tank pressure control system function problem 337
P1402 FLVL Fuel level sensor circuit malfunction 339
P1500 FAN
—1 Radiator fan relay 1 circuit malfunction 351
P1502 FAN
—F Radiator fan function problem 358
P1700 ATTH Throttle position sensor circuit malfunction for automatic transmission 361
P1701 ATCRS Cruise control set signal circuit malfunction for automatic transmission 362
P1702 ATDIAG Automatic transmission diagnosis input signal circuit malfunction 365
P0461*1 EXERR22 Fuel level sensor circuit range/performance problem 368
*1: Only OBD-II general scan tool displays DTC.
124
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

OBD0142
B: DTC P0100
—MASS AIR FLOW SENSOR CIRCUIT
MALFUNCTION (QA)—
DTC DETECTING CONDITION:

Immediately at fault recognition
TROUBLE SYMPTOM:

Erroneous idling

Engine stalls.

Poor driving performance
10B1Connect Subaru Select Monitor or the OBD-II
general scan tool, and read data.10B5Check harness between ECM and mass air
flow sensor connector.
10B2Check input signal for ECM. (Using voltage
meter and Subaru Select Monitor.)
10B3Check power supply to mass air flow sensor.
10B4Check harness between ECM and mass air
flow sensor connector.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.




125
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:

LHD Model
B2M0531
126
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

WIRING DIAGRAM:

RHD Model
B2M0785
127
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

OBD0145A
10B1CONNECT SUBARU SELECT MONITOR
OR THE OBD-II GENERAL SCAN TOOL,
AND READ DATA.
1) Turn ignition switch to OFF.
2) Connect Subaru Select Monitor or the OBD-II general
scan tool to data link connector.
3) Turn ignition switch to ON and Subaru Select Monitor or
the OBD-II general scan tool switch to ON.
4) Start engine.
B2M0481
5) Read data on Subaru Select Monitor or OBD-II general
scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F06

F06: Mass air flow and voltage input from mass air flow
sensor are shown on display at the same time.
: Is the value equal to or more than 1.3 g/sec
or 0.3 V and equal to or less than 250 g/sec
or 5.0 V in function mode F06?
Probable cause: Poor connect of connectors, circuit and
grounding line.
: Even if MIL lights up, the circuit has returned to a
normal condition at this time. A temporary poor
contact of the connector or harness may be the
cause. Repair harness or connector in the mass
air flow sensor.
NOTE:
In this case, repair the following:

Open or short circuit in harness between mass air flow
sensor and ECM connector

Poor contact in mass air flow sensor or ECM connector
: Go to next.
B2M0481
: Is the value less than 1.3 g/sec or 0.3 V in
function mode F06?
: Go to step10B2.
: Go to step10B5.

OBD-II general scan tool
For detailed operation procedures, refer to the OBD-II Gen-
eral Scan Tool Instruction Manual.
128
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

B2M0532A
10B2CHECK INPUT SIGNAL FOR ECM.
(USING VOLTAGE METER AND SUBARU
SELECT MONITOR.)
Measure voltage between ECM connector and chassis
ground while engine is idling.
: Connector & terminal
(B84) No. 5 (+)—Chassis ground ():
Is the voltage less than 0.3 V?
: Go to step10B3.
: Go to next.
B2M0481
: Does the voltage change more than 0.3 V by
shaking harness and connector of ECM
while monitoring the value with Subaru
select monitor?
: Repair poor contact in ECM connector.
: Replace ECM.
B2M0645A
10B3CHECK POWER SUPPLY TO MASS AIR
FLOW SENSOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from mass air flow sensor.
3) Turn ignition switch to ON.
4) Measure voltage between mass air flow sensor connec-
tor and engine ground.
: Connector & terminal
(B3) No. 1 (+)—Engine ground ():
Is the voltage more than 10 V?
: Go to step10B4.
: Repair open circuit in harness between main relay
and mass air flow sensor connector.
129
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

B2M0533A
10B4CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
1) Turn ignition switch to OFF.
2) Disconnect connector from ECM.
3) Measure resistance of harness between ECM and
mass air flow sensor connector.
: Connector & terminal
(B84) No. 5—(B3) No. 4:
Is the resistance less than 1Ω?
: Go to next.
: Repair harness and connector.
NOTE:
In this case, repair the following:

Open circuit in harness between ECM and mass air flow
sensor connector

Poor contact in mass air flow sensor connector

Poor contact in ECM connector
: Connector & terminal
(B84) No. 18—(B3) No. 3:
Is the resistance less than 1Ω?
: Go to next.
: Repair harness and connector.
NOTE:
In this case, repair the following:

Open circuit in harness between ECM and mass air flow
sensor connector

Poor contact in mass air flow sensor connector

Poor contact in ECM connector
: Connector & terminal
(B84) No. 20—(B3) No. 2:
Is the resistance less than 1Ω?
: Replace mass air flow sensor.
: Repair harness and connector.
NOTE:
In this case, repair the following:

Open circuit in harness between ECM and mass air flow
sensor connector

Poor contact in mass air flow sensor connector

Poor contact in ECM connector
130
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

B2M0481
10B5CHECK HARNESS BETWEEN ECM AND
MASS AIR FLOW SENSOR CONNECTOR.
1) Turn ignition switch to OFF and Subaru Select Monitor
or the OBD-II general scan tool switch to OFF.
2) Disconnect connector from mass air flow sensor.
3) Turn ignition switch to ON and Subaru Select Monitor or
the OBD-II general scan tool switch to ON.
4) Read data on Subaru select monitor or OBD-II general
scan tool.

Subaru Select Monitor
Designate mode using function key.
Function mode: F06
: Is the value more than 250 g/sec or5Vin
function mode F06?
: Repair short circuit in harness between mass air
flow sensor and ECM connector.
: Go to next.
: Is there poor contact in mass air flow sensor
connector?
: Repair poor contact in mass air flow sensor con-
nector.
: Replace mass air flow sensor.

OBD-II general scan tool
For detailed operation procedures, refer to OBD-II General
Scan Tool Instruction Manual.
131
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code

OBD0152
C: DTC P0101
—MASS AIR FLOW SENSOR CIRCUIT
RANGE/PERFORMANCE PROBLEM
(QA
—R)—
DTC DETECTING CONDITION:

Two consecutive trips with fault
TROUBLE SYMPTOM:

Erroneous idling

Engine stalls.

Poor driving performance
10C1Check DTC P0100 on display.
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

WIRING DIAGRAM:

LHD Model
B2M0531
132
2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostics Chart with Trouble Code