sensor SUBARU LEGACY 1997 Service Repair Manual

Symptom Problem parts
7. Spark knock1) Mass air flow sensor
2) Engine coolant temperature sensor
3) Knock sensor
4) Fuel injection parts (*4)
5) Fuel pump and fuel pump relay
8. After burning in exhaust system1) Mass air flow sensor
2) Engine coolant temperature sensor (*2)
3) Fuel injection parts (*4)
4) Fuel pump and fuel pump relay
*1: Check ignitor, ignition coil and spark plug.
*2: Indicate the symptom occurring only in cold temperatures.
*3: Ensure the secure installation.
*4: Check fuel injector, fuel pressure regulator and fuel filter.
*5: Inspect air leak in air intake system.
*6: Adjust accelerator cable.
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
9. General Diagnostic Table

B: GENERAL DIAGNOSTICS TABLE WITH
NONCONFORMITY SYMPTOM FOR
AUTOMATIC TRANSMISSION
Problem parts
Inhibitor switch
Control module
Vehicle speed sensor 1
Vehicle speed sensor 2
Select cable
Select lever
FWD switch
Starter motor and harness
Throttle position sensor
Hold switch
Accumulator (“N”—“D”)
Accumulator (2A)
Accumulator (4A)
Accumulator (3R)
ATF temperature sensor
Strainer
Duty solenoid A
Duty solenoid B
Shift solenoid 1
Shift solenoid 2
Shift solenoid 3
Control valve
Detent spring
Manual plate
Transfer clutch
Transfer valve
Transfer pipe
Duty solenoid C
Forward clutch
Symptom1234567891011121314151617181920212223242526272829
Starter does not rotate when select lever is
in“P”or“N.”; starter rotates when select
lever is“R”,“D”,“3”or“2.”
Abnormal noise when select lever is in“P”or
“N.”
Hissing noise occurs during standing starts.
Noise occurs while driving in“D
1”range.
Noise occurs while driving in“D
2”range.
Noise occurs while driving in“D
3”range.
Noise occurs while driving in“D
4”range.
Engine stalls while shifting from one range to
another.
Vehicle moves when select lever is in“N.”
Shock occurs when select lever is moved
from“N”to“D.” 
Excessive time lag occurs when select lever
is moved from“N”to“D.”
Shock occurs when select lever is moved
from“N”to“R.”
Excessive time lag occurs when select lever
is moved from“N”to“R.”
Vehicle does not start in any shift range
(engine revving up).
Vehicle does not start in any shift range
(engine stall).
Vehicle does not start in“R”range only
(engine revving up). 
Vehicle does not start in“R”range only
(engine stall).
Vehicle does not start in“D”or“3”range
(engine revving up).
Vehicle does not start in“D”,“3”or“2”range
(engine revving up).
Vehicle does not start in“D”,“3”or“2”range
(engine stall).
Vehicle starts in“R”range only (engine rev-
ving up).
Acceleration during standing starts is poor
(high stall rpm).
Acceleration during standing starts is poor
(low stall rpm).
Acceleration is poor when select lever is in
“D”,“3”or“2”range (normal stall rpm).
Acceleration is poor when select lever is in
“R”(normal stall rpm).
No shift occurs from 1st to 2nd gear.   
No shift occurs from 2nd to 3rd gear.
No shift occurs from 3rd to 4th gear.
No“kick-down”shifts occur.
Engine brake is not effected when select
lever is in“3”range.  
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
9. General Diagnostic Table

Problem parts
Inhibitor switch
Control module
Vehicle speed sensor 1
Vehicle speed sensor 2
Select cable
Select lever
FWD switch
Starter motor and harness
Throttle position sensor
Hold switch
Accumulator (“N”—“D”)
Accumulator (2A)
Accumulator (4A)
Accumulator (3R)
ATF temperature sensor
Strainer
Duty solenoid A
Duty solenoid B
Shift solenoid 1
Shift solenoid 2
Shift solenoid 3
Control valve
Detent spring
Manual plate
Transfer clutch
Transfer valve
Transfer pipe
Duty solenoid C
Forward clutch
Symptom1234567891011121314151617181920212223242526272829
Engine brake is not effected when select
lever is in“3”or“2”range.
Engine brake is not effected when select
lever is in“1”range.
Shift characteristics are erroneous.  
No lock-up occurs.
Vehicle cannot be set in“D”range power
mode.
“D”range power mode cannot be released.
Parking brake is not effected.
Shift lever cannot be moved or is hard to
move from“P”range.
Select lever is hard to move. 
Select lever is too light to move (unreason-
able resistance).
ATF spurts out.
Differential oil spurts out.
Differential oil level changes excessively.
Odor is produced from oil supply pipe.
Shock occurs when select lever is moved
from“1”to“2”range.  
Slippage occurs when select lever is moved
from“1”to“2”range.  
Shock occurs when select lever is moved
from“2”to“3”range.
Slippage occurs when select lever is moved
from“2”to“3”range.
Shock occurs when select lever is moved
from“3”to“4”range.   
Slippage occurs when select lever is moved
from“3”to“4”range.   
Shock occurs when select lever is moved
from“3”to“2”range.
Shock occurs when select lever is moved
from“D”to“1”range.
Shock occurs when select lever is moved
from“2”to“1”range.
Shock occurs when accelerator pedal is
released at medium speeds.
Vibration occurs during straight-forward
operation.
Select lever slips out of position during
acceleration or while driving on rough terrain. 
Vibration occurs during turns (tight corner
“braking”phenomenon).    
Front wheel slippage occurs during standing
starts.      
Vehicle is not set in FWD mode. 
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
9. General Diagnostic Table

10. Diagnostic Chart with Trouble Code
for LHD Vehicles
A: DIAGNOSTIC TROUBLE CODE (DTC) LIST
DTC
No.Abbreviation
(Subaru Select Monitor)Item Page
P0101 QA
—RLOW Mass air flow sensor circuit range/performance problem (low input) 132
P0102 QA
—LOW Mass air flow sensor circuit low input 134
P0103 QA
—HI Mass air flow sensor circuit high input 138
P0106 PS
—R2 Pressure sensor circuit range/performance problem 141
P0107 P
—SLOW Pressure sensor circuit low input 145
P0108 P
—SHI Pressure sensor circuit high input 149
P0116 TW
—LOW Engine coolant temperature sensor circuit low input 154
P0117 TW
—HI Engine coolant temperature sensor circuit high input 157
P0121 TH
—RHI Throttle position sensor circuit range/performance problem (high input) 160
P0122 THV
—LOW Throttle position sensor circuit low input 162
P0123 THV
—HI Throttle position sensor circuit high input 167
P0125 TW
—CL Insufficient coolant temperature for closed loop fuel control 170
P0130 FO2
—V Front oxygen sensor circuit malfunction 172
P0133 FO2
—R Front oxygen sensor circuit slow response 175
P0135 FO2H Front oxygen sensor heater circuit malfunction 177
P0136 RO2
—V Rear oxygen sensor circuit malfunction 181
P0139 RO2
—R Rear oxygen sensor circuit slow response 184
P0141 RO2H Rear oxygen sensor heater circuit malfunction 186
P0170 FUEL Fuel trim malfunction 190
P0181 TNKT
—F Fuel temperature sensor A circuit range/performance problem 195
P0182 TNKT
—LOW Fuel temperature sensor A circuit low input 197
P0183 TNKT
—HI Fuel temperature sensor A circuit high input 200
P0261 INJ1 Fuel injector circuit low input - #1 203
P0262 INJ1
—HI Fuel injector circuit high input - #1 207
P0264 INJ2 Fuel injector circuit low input - #2 203
P0265 INJ2
—HI Fuel injector circuit high input - #2 207
P0267 INJ3 Fuel injector circuit low input - #3 203
P0268 INJ3
—HI Fuel injector circuit high input - #3 207
P0270 INJ4 Fuel injector circuit low input - #4 203
P0271 INJ4
—HI Fuel injector circuit high input - #4 207
P0301 MIS
—1 Cylinder 1 misfire detected 211
P0302 MIS
—2 Cylinder 2 misfire detected 211
P0303 MIS
—3 Cylinder 3 misfire detected 211
P0304 MIS
—4 Cylinder 4 misfire detected 211
P0325 KNOCK Knock sensor circuit malfunction 219
P0335 CRANK Crankshaft position sensor circuit malfunction 222
P0336 CRANK
—R Crankshaft position sensor circuit range/performance problem 225
P0340 CAM Camshaft position sensor circuit malfunction 227
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

DTC
No.Abbreviation
(Subaru Select Monitor)Item Page
P0341 CAM
—R Camshaft position sensor circuit range/performance problem 230
P0400 EGR Exhaust gas recirculation flow malfunction 232
P0403 EGRSOL Exhaust gas recirculation circuit low input 237
P0420 CAT Catalyst system efficiency below threshold 240
P0440 EVAP Evaporative emission control system malfunction 242
P0441 CPC
—F Evaporative emission control system incorrect purge flow 246
P0443 CPC Evaporative emission control system purge control valve circuit low input 248
P0446 VCMSOL
—LO Evaporative emission control system vent control low input 251
P0451 TNKP
—F Evaporative emission control system pressure sensor range/performance problem 254
P0452 TNKP
—LOW Evaporative emission control system pressure sensor low input 256
P0453 TNKP
—HI Evaporative emission control system pressure sensor high input 261
P0461 FLVL
—R Fuel level sensor circuit range/performance problem 267
P0462 FLVL
—LOW Fuel level sensor circuit low input 269
P0463 FLVL
—HI Fuel level sensor circuit high input 275
P0500 VSP Vehicle speed sensor malfunction 281
P0505 ISC Idle control system malfunction 283
P0506 ISC
—RLOW Idle control system RPM lower than expected 289
P0507 ISC
—RHI Idle control system RPM higher than expected 291
P0600—Serial communication link malfunction 293
P0601 RAM Internal control module memory check sum error 295
P0703 ATBRK Brake switch input malfunction 296
P0705 ATRNG Transmission range sensor circuit malfunction 299
P0710 ATF Transmission fluid temperature sensor circuit malfunction 311
P0720 ATVSP Output speed sensor (vehicle speed sensor 1) circuit malfunction 312
P0725 ATNE Engine speed input circuit malfunction 313
P0731 ATGR1 Gear 1 incorrect ratio 314
P0732 ATGR2 Gear 2 incorrect ratio 314
P0733 ATGR3 Gear 3 incorrect ratio 314
P0734 ATGR4 Gear 4 incorrect ratio 314
P0740 ATLU
—F Torque converter clutch system malfunction 317
P0743 ATLU Torque converter clutch system electrical 321
P0748 ATPL Pressure control solenoid electrical 322
P0753 ATSFT1 Shift solenoid A electrical 323
P0758 ATSFT2 Shift solenoid B electrical 324
P0760 ATOVR
—F Shift solenoid C malfunction 325
P0763 ATOVR Shift solenoid C electrical 328
P1100 ST
—SWOFF Starter switch circuit low input 329
P1101 N
—SW Neutral position switch circuit malfunction [MT vehicles] 331
P1101 N
—SWOFF Neutral position switch circuit high input [AT vehicles] 335
P1102 BR Pressure sources switching solenoid valve circuit low input 340
P1103 TRQ Engine torque control signal circuit malfunction 343
P1104 TCS
—LOW TCS signal circuit low input 346
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

DTC
No.Abbreviation
(Subaru Select Monitor)Item Page
P1120 ST
—SWON Starter switch circuit high input 348
P1121 N
—SWON Neutral position switch circuit low input [AT vehicles] 350
P1122 BR
—HI Pressure sources switching solenoid valve circuit high input 354
P1124 TCS
—HI TCS signal circuit high input 357
P1141 QA
—RHI Mass air flow sensor circuit range/performance problem (high input) 360
P1142 TH
—RLOW Throttle position sensor circuit range/performance problem (low input) 362
P1143 PS
—RLOW Pressure sensor circuit range/performance problem (low input) 364
P1144 PS
—RHI Pressure sensor circuit range/performance problem (high input) 368
P1400 PCVSOL
—LO Fuel tank pressure control solenoid valve circuit low input 370
P1420 PCVSOL
—HI Fuel tank pressure control solenoid valve circuit high input 374
P1421 EGRSOL
—HI Exhaust gas recirculation circuit high input 377
P1422 CPC
—HI Evaporative emission control system purge control valve circuit high input 380
P1423 VCMSOL
—HI Evaporative emission control system vent control high input 383
P1440 PCV
—FLOW Fuel tank pressure control system function problem (low input) 386
P1441 PCV
—FHI Fuel tank pressure control system function problem (high input) 390
P1442 FLVL
—R2 Fuel level sensor circuit range/performance problem 2 393
P1500 FAN
—1 Radiator fan relay 1 circuit low input 395
P1502 FAN
—F Radiator fan function problem 401
P1507 ISC
—SHI Idle control system malfunction (fail-safe) 403
P1520 FAN
—1HI Radiator fan relay 1 circuit high input 405
P1540 VSP
—S Vehicle speed sensor malfunction 2 407
P1700 ATTH Throttle position sensor circuit malfunction for automatic transmission 409
P1701 ATCRS Cruise control set signal circuit malfunction for automatic transmission 411
P1702 ATDIAG
—LO Automatic transmission diagnosis input signal circuit low input 413
P1722 ATDIAG
—HI Automatic transmission diagnosis input signal circuit high input 416
P1742 ATDIAG
—2 Automatic transmission diagnosis input signal circuit malfunction 419
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

B2M1056
B: DTC P0101
—MASS AIR FLOW SENSOR CIRCUIT
RANGE/PERFORMANCE PROBLEM
(LOW INPUT)—
DTC DETECTING CONDITION:

Two consecutive driving cycles with fault
TROUBLE SYMPTOM:

Erroneous idling

Engine stalls.

Poor driving performance
WIRING DIAGRAM:
B2M1057
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

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2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

10B1CHECK DTC P0102 OR P0103 ON DIS-
PLAY.
: Does the Subaru select monitor or OBD-II
general scan tool indicate DTC P0102 or
P0103?
: Inspect DTC P0102 or P0103 using“10. Diagnos-
tics Chart with Trouble Code”. [T10A0].>
NOTE:
In this case, it is not necessary to inspect DTC P0101.
: Replace mass air flow sensor.
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

B2M1058
C: DTC P0102
—MASS AIR FLOW SENSOR CIRCUIT LOW
INPUT—
DTC DETECTING CONDITION:

Immediately at fault recognition
TROUBLE SYMPTOM:

Erroneous idling

Engine stalls.

Poor driving performance
WIRING DIAGRAM:
B2M1057
CAUTION:
After repair or replacement of faulty parts, conduct
CLEAR MEMORY and INSPECTION MODES.

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2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles

OBD0145A
10C1CONNECT 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 ground short circuit in harness between mass
air flow sensor and ECM connector

Poor contact in mass air flow sensor or ECM connector
: Go to step10C2.
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2-7ON-BOARD DIAGNOSTICS II SYSTEM
10. Diagnostic Chart with Trouble Code for LHD Vehicles