Page 1435 of 2453
EN(H6DO)(diag)-274
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
6CHECK POWER SUPPLY TO DRAIN VALVE.
1) Turn the ignition switch to ON.
2) Measure the voltage between drain valve
and chassis ground.
Connector & terminal
(R143) No. 1 (+) — Chassis ground (–):
Is the voltage more than 10 V? Go to step 7.Repair the har-
ness and connec-
tor.
NOTE:In this case, repair
the following item:
•Open circuit
of harness be-
tween main re-
lay and drain
valve
•Poor contact
of coupling con-
nector
•Poor contact
of main relay
connector
7CHECK POOR CONTACT.
Check poor contact in drain valve connector.
Is there poor contact in drain
valve connector?
Repair poor con-
tact in drain valve
connector.
Contact with SOA
Service Center.
Step Check Yes No
Page 1436 of 2453
EN(H6DO)(diag)-275
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CE:DTC P0448 EVAPORATIVE EMISSION CONTROL SYSTEM VENT CONTROL
CIRCUIT SHORTED
DTC DETECTING CONDITION:
•Immediately at fault recognition
•GENERAL DESCRIPTION
SYSTEM VENT CONTROL CIRCUIT SHORTED, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode
OPERATION, Clear Memory Mode.> and Inspection Mode
Inspection Mode.>.
WIRING DIAGRAM:
EN-03666
SBF-7
R143R60
R60
R15
R15
R1
R1
B98
B98
B47
ECM
E
17
12
53
64
21
13
9
5
B136
CANISTER
DRAINVA LV E
MAIN RELAYBATTERY
7
B47
3412
56
R143
12
B98
123456 78910 1112 13 16 1714 15 18 19 2021222324
B136
16101112131415252430
9871718192028212223293231
123456
2726333435
R60
12
10115634897131412
Page 1437 of 2453

EN(H6DO)(diag)-276
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1CHECK INPUT SIGNAL OF ECM.
1) Turn the ignition switch to OFF.
2) Connect the test mode connector at the
lower portion of instrument panel (on the
driver’s side).
3) Turn the ignition switch to ON.
4) While operating the drain valve, measure
voltage between ECM and chassis ground.
NOTE:
Drain valve operation can also be executed us-
ing Subaru Select Monitor. Refer to “Compulso-
ry Valve Operation Check Mode” for
procedures.
Compulsory Valve Operation Check Mode.>
Connector & terminal
(B136) No. 17 (+) — Chassis ground (–):
Is the voltage 0 — 10 V? Go to step 2.Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time. In this
case, repair the
poor contact in
ECM connector.
2CHECK INPUT SIGNAL OF ECM.
1) Turn the ignition switch to ON.
2) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 17 (+) — Chassis ground (–):
Is the voltage more than 10 V? Go to step 4.Go to step 3.
3CHECK POOR CONTACT.
Check poor contact of ECM connector.
Is there poor contact in ECM
connector?
Repair poor con-
tact in ECM con-
nector.
Replace the ECM.
FU(H6DO)-32,
Engine Control
Module (ECM).>
4CHECK HARNESS BETWEEN DRAIN
VALVE AND ECM CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from the drain
valve.
3) Turn the ignition switch to ON.
4) Measure the voltage between ECM and
chassis ground.
Connector & terminal
(B136) No. 17 (+) — Chassis ground (–):
Is the voltage more than 10 V? Repair battery
short circuit of har-
ness between
ECM and drain
valve connector.
After repair,
replace the ECM.
FU(H6DO)-32,
Engine Control
Module (ECM).>
Go to step 5.
5CHECK DRAIN VALVE.
1) Turn the ignition switch to OFF.
2) Measure the resistance between drain
valve terminals.
Te r m i n a l s
No. 1 — No. 2:
Is the resistance less than 1
Ω?
Replace the drain
valve
EC(H6DO)-12,
Drain Valve.> and
ECM
FU(H6DO)-32,
Engine Control
Module (ECM).>.
Go to step 6.
6CHECK POOR CONTACT.
Check poor contact of ECM connector.
Is there poor contact in ECM
connector?
Repair poor con-
tact in ECM con-
nector.
Replace the ECM.
FU(H6DO)-32,
Engine Control
Module (ECM).>
Page 1438 of 2453
EN(H6DO)(diag)-277
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CF:DTC P0451 EVAPORATIVE EMISSION CONTROL SYSTEM PRESSURE
SENSOR
DTC DETECTING CONDITION:
•Detected when two consecutive driving cycles with fault occur.
•GENERAL DESCRIPTION
SYSTEM PRESSURE SENSOR, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode
OPERATION, Clear Memory Mode.> and Inspection Mode
Inspection Mode.>.
WIRING DIAGRAM:
EN-03667
B424
312
223230
ECMB135
R47
R60
R15
R1
B98
123
R47
11210
192018
FUEL TANKPRESSURESENSOR
B424
34561278
: TERMINAL NO. OPTIONAL ARRANGEMENT*
**
B98
123456 78910 1112 13 16 1714 15 18 19 2021222324
R60
12
10115634897131412
B135
567821943102422 23 2511 12 13 14 1526 2728
16 17 18 1920 2129 30 31 32 33 34 35
Page 1439 of 2453
EN(H6DO)(diag)-278
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1CHECK ANY OTHER DTC ON DISPLAY.Is any other DTC displayed? Check the appro-
priate DTC using
the “List of Diag-
nostic Trouble
Code (DTC)”.
EN(H6DO)(diag)-
69, List of Diag-
nostic Trouble
Code (DTC).>
Go to step 2.
2CHECK FUEL FILLER CAP.
1) Turn the ignition switch to OFF.
2) Open the fuel flap.
Is the fuel filler cap tightened
securely?
Go to step 3.Tighten fuel filler
cap securely.
3CHECK PRESSURE VACUUM LINE.
NOTE:Check the following item.
•Disconnection, leakage and clogging of the
vacuum hoses and pipes between fuel tank
pressure sensor and fuel tank
•Disconnection, leakage and clogging of the
air ventilation hoses and pipes between fuel fill-
er pipe and fuel tank
Is there a fault in pressure/vac-
uum line?
Repair or replace
the hoses and
pipes.
Replace the fuel
tank pressure sen-
sor.
EC(H6DO)-10,
Fuel Tank Pres-
sure Sensor.>
Page 1440 of 2453
EN(H6DO)(diag)-279
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
CG:DTC P0452 EVAPORATIVE EMISSION CONTROL SYSTEM PRESSURE
SENSOR LOW INPUT
DTC DETECTING CONDITION:
•Immediately at fault recognition
•GENERAL DESCRIPTION
SYSTEM PRESSURE SENSOR LOW INPUT, Diagnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:
After repair or replacement of faulty parts, perform Clear Memory Mode
OPERATION, Clear Memory Mode.> and Inspection Mode
Inspection Mode.>.
WIRING DIAGRAM:
EN-03667
B424
312
223230
ECMB135
R47
R60
R15
R1
B98
123
R47
11210
192018
FUEL TANKPRESSURESENSOR
B424
34561278
: TERMINAL NO. OPTIONAL ARRANGEMENT*
**
B98
123456 78910 1112 13 16 1714 15 18 19 2021222324
R60
12
10115634897131412
B135
567821943102422 23 2511 12 13 14 1526 2728
16 17 18 1920 2129 30 31 32 33 34 35
Page 1441 of 2453

EN(H6DO)(diag)-280
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step Check Yes No
1CHECK CURRENT DATA.
1) Turn the ignition switch to OFF.
2) Remove the fuel filler cap.
3) Install the fuel filler cap.
4) Turn the ignition switch to ON.
5) Read the data of fuel tank pressure sensor
signal using Subaru Select Monitor.
NOTE:•Subaru Select Monitor
For detailed operation procedures, refer to
“READ CURRENT DATA FOR ENGINE”.
to EN(H6DO)(diag)-26, Subaru Select Moni-
tor.>
Is the measured value less
than –2.8 kPa (–21.0 mmHg, –
0.827 inHg)?
Go to step 2.Even if the mal-
function indicator
light illuminates,
the circuit has
returned to a nor-
mal condition at
this time.
2CHECK POWER SUPPLY TO FUEL TANK
PRESSURE SENSOR.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 22 (+) — Chassis ground (–):
Is the voltage more than 4.5 V? Go to step 4.Go to step 3.
3CHECK POWER SUPPLY TO FUEL TANK
PRESSURE SENSOR.
Measure the voltage between ECM connector
and chassis ground.
Connector & terminal
(B135) No. 22 (+) — Chassis ground (–):
Does the voltage change by
shaking the ECM harness and
connector?
Repair poor con-
tact in ECM con-
nector.
Contact with SOA
Service Center.
4CHECK INPUT SIGNAL OF ECM.
Measure the voltage between ECM and chas-
sis ground.
Connector & terminal
(B135) No. 32 (+) — Chassis ground (–):
Is the voltage less than 0.2 V? Go to step 6.Go to step 5.
5CHECK INPUT SIGNAL FOR ECM (USING
SUBARU SELECT MONITOR).
Read the data of fuel tank pressure sensor sig-
nal using Subaru Select Monitor.
NOTE:
•Subaru Select Monitor
For detailed operation procedure, refer to
“READ CURRENT DATA FOR ENGINE”.
to EN(H6DO)(diag)-26, Subaru Select Moni-
tor.>
Does the measured value
change by shaking ECM har-
ness and connector?
Repair poor con-
tact in ECM con-
nector.
Go to step 6.
6CHECK HARNESS BETWEEN ECM AND
COUPLING CONNECTOR IN REAR WIRING
HARNESS.
1) Turn the ignition switch to OFF.
2) Remove the rear seat cushion.
3) Separate rear wiring harness and fuel tank
cord.
4) Turn the ignition switch to ON.
5) Measure the voltage between rear wiring
harness connector and chassis ground.
Connector & terminal
(R15) No. 11 (+) — Chassis ground (–):
Is the voltage more than 4.5 V? Go to step 7.Repair the har-
ness and connec-
tor.
NOTE:In this case, repair
the following item:
•Open circuit
of harness be-
tween ECM and
rear wiring har-
ness connector
•Poor contact
of coupling con-
nector
Page 1442 of 2453

EN(H6DO)(diag)-281
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
7CHECK HARNESS BETWEEN ECM AND
COUPLING CONNECTOR IN REAR WIRING
HARNESS.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from ECM.
3) Measure the resistance of harness
between ECM and rear wiring harness con-
nector.
Connector & terminal
(B135) No. 30 — (R15) No. 2:
Is the resistance less than 1
Ω?
Go to step 8.Repair the har-
ness and connec-
tor.
NOTE:In this case, repair
the following item:
•Open circuit
of harness be-
tween ECM and
rear wiring har-
ness connector
•Poor contact
of coupling con-
nector
•Poor contact
of joint connec-
tor
8CHECK HARNESS BETWEEN ECM AND
COUPLING CONNECTOR IN REAR WIRING
HARNESS.
Measure the resistance of harness between
rear wiring harness connector and chassis
ground.
Connector & terminal
(R15) No. 2 — Chassis ground:
Is the resistance more than 1
MΩ?
Go to step 9.Repair short circuit
to ground in har-
ness between
ECM and rear wir-
ing harness con-
nector.
9CHECK FUEL TANK CORD.
1) Disconnect the connector from fuel tank
pressure sensor.
2) Measure the resistance of fuel tank cord.
Connector & terminal
(R60) No. 11 — (R47) No. 3:
Is the resistance less than 1
Ω?
Go to step 10.Repair open circuit
in fuel tank cord.
10 CHECK FUEL TANK CORD.
Measure the resistance of fuel tank cord.
Connector & terminal
(R60) No. 2 — (R47) No. 1:
Is the resistance less than 1
Ω?
Go to step 11.Repair open circuit
in fuel tank cord.
11 CHECK FUEL TANK CORD.
Measure the resistance of harness between
fuel tank pressure sensor connector and
engine ground.
Connector & terminal
(R47) No. 2 — Chassis ground:
Is the resistance more than 1
MΩ?
Go to step 12.Repair ground
short circuit in fuel
tank cord.
12 CHECK POOR CONTACT.
Check poor contact in fuel tank pressure sen-
sor connector.
Is there poor contact in fuel
tank pressure sensor connec-
tor?
Repair poor con-
tact in fuel tank
pressure sensor
connector.
Replace the fuel
tank pressure sen-
sor.
EC(H6DO)-10,
Fuel Tank Pres-
sure Sensor.>
Step Check Yes No