Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 263

EN(H4DOTC)(diag)-276

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

Step

Check

Yes

CHECK BLOW-BY HOSE.
Check the blow-by hose condition.

Is there any disconnection or
crack in blow-by hose?

Install or replace
the blow-by hose.

Go to step

CHECK HARNESS BETWEEN ECM AND
PCV HOSE ASSEMBLY CONNECTOR.
1) Turn the ignition switch to OFF.
2) Disconnect the connectors from the ECM
and PCV hose assembly.
3) Measure the resistance of harness between
ECM connector and PCV hose assembly con-
nector.

Connector & terminal

(B137) No. 12 — (E80) No. 2:

Is the resistance less than 1 Ω? Go to step

Repair the harness
and connector.
NOTE:

In this case, repair
the following item:
• Open circuit in
harness between
ECM

connector

and PCV hose as-
sembly connector
• Poor contact of
coupling connector

CHECK HARNESS BETWEEN ECM AND
PCV HOSE ASSEMBLY CONNECTOR.
Measure the resistance between PCV hose
assembly connector and chassis ground.

Connector & terminal

(B137) No. 12 — Chassis ground:

Is the resistance 1 MΩ or
more?

Go to step

Repair the short
circuit to ground in
harness between
ECM connector
and PCV hose
assembly connec-
tor.

CHECK HARNESS BETWEEN LEAK DIAG-
NOSIS CONNECTORS.
Measure the resistance of harness between
leak diagnosis connectors.

Connector & terminal

Models without SI-DRIVE

(B80) No. 1 — (B87) No. 1:
(B87) No. 2 — (B88) No. 1:

Models with SI-DRIVE

(B80) No. 1 — (B87) No. 1:

Is the resistance less than 1 Ω? Go to step

Repair the open
circuit in the wiring
harness between
leak diagnosis
connectors.

CHECK GROUND CIRCUIT OF PCV HOSE
ASSEMBLY.
Measure the resistance of harness between
PCV hose assembly connector and engine
ground.

Connector & terminal

Models without SI-DRIVE

(B88) No. 2 — Engine ground:

Models with SI-DRIVE

(B87) No. 2 — Engine ground:

Is the resistance less than 5 Ω? Go to step

Repair the open
circuit in harness
between PCV
hose assembly
connector and
engine ground.

CHECK PCV HOSE ASSEMBLY.
Measure the resistance between terminals of
each leak diagnosis connector.

Terminals

No. 1 — No. 2:

Is the resistance less than 1 Ω
at all measurement?

Repair the poor
contact of ECM
and PCV hose
assembly connec-
tor.

Replace the PCV
hose assembly.
<Ref. to EC(STI)-
24, PCV Hose
Assembly.> <Ref.
to EC(w/o STI)-25,
PCV Hose Assem-
bly.>

EN(H4DOTC)(diag)-277

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CU:DTC P0500 VEHICLE SPEED SENSOR “A”

DTC DETECTING CONDITION:

• Immediately at fault recognition

• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-182, DTC P0500 VEHICLE SPEED SENSOR “A”, Di-

agnostic Trouble Code (DTC) Detecting Criteria.>
CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-63,

OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-49, PROCE-

DURE, Inspection Mode.>.

Step

Check

Yes

CHECK DTC OF VDC.
Check DTC of VDC.

Is DTC of VDC displayed?

Perform the diag-
nosis according to
DTC. <Ref. to
VDC(diag)-48, List
of Diagnostic Trou-
ble Code (DTC).>

Repair the poor
contact of ECM
connector.

EN(H4DOTC)(diag)-278

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CV:DTC P0506 IDLE AIR CONTROL SYSTEM RPM LOWER THAN EXPECTED

DTC DETECTING CONDITION:

• Detected when two consecutive driving cycles with fault occur.

• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-183, DTC P0506 IDLE AIR CONTROL SYSTEM RPM

LOWER THAN EXPECTED, Diagnostic Trouble Code (DTC) Detecting Criteria.>

TROUBLE SYMPTOM:

• Hard to start the engine.

• Engine does not start.

• Improper idling

• Engine stalls.
CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-63,

OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-49, PROCE-

DURE, Inspection Mode.>.

Step

Check

Yes

CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed?

Check the appropri-
ate DTC using the
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H4DOTC)(diag)
-87, List of Diagnos-
tic Trouble Code
(DTC).>

Go to step

CHECK AIR CLEANER ELEMENT.
1) Turn the ignition switch to OFF.
2) Check the air cleaner element.

Is there excessive clogging on
air cleaner element?

Replace the air
cleaner element.
<Ref. to IN(STI)-7,
Air Cleaner Ele-
ment.> <Ref. to
IN(w/o STI)-7, Air
Cleaner Element.>

Go to step

CHECK ELECTRONIC THROTTLE CON-
TROL.
1) Remove the electronic throttle control.
<Ref. to FU(STI)-15, REMOVAL, Throttle
Body.> <Ref. to FU(w/o STI)-15, REMOVAL,
Throttle Body.>
2) Check the electronic throttle control.

Are foreign matter found inside
electronic throttle control?

Remove foreign
matter from elec-
tronic throttle con-
trol.

Perform the diagno-
sis of DTC P2101.
<Ref. to
EN(H4DOTC)(diag)
-371, DTC P2101
THROTTLE ACTU-
ATOR CONTROL
MOTOR CIRCUIT
RANGE/PERFOR-
MANCE, Diagnos-
tic Procedure with
Diagnostic Trouble
Code (DTC).>

EN(H4DOTC)(diag)-279

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ENGINE (DIAGNOSTICS)

CW:DTC P0507 IDLE AIR CONTROL SYSTEM RPM HIGHER THAN EXPECTED

DTC DETECTING CONDITION:

• Detected when two consecutive driving cycles with fault occur.

• GENERAL DESCRIPTION <Ref. to GD(H4DOTC)-184, DTC P0507 IDLE AIR CONTROL SYSTEM RPM

HIGHER THAN EXPECTED, Diagnostic Trouble Code (DTC) Detecting Criteria.>

TROUBLE SYMPTOM:

Engine keeps running at higher speed than specified idle speed.
CAUTION:

After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(H4DOTC)(diag)-63,

OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4DOTC)(diag)-49, PROCE-

DURE, Inspection Mode.>.

Step

Check

Yes

CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed?

Check the appropri-
ate DTC using the
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
EN(H4DOTC)(diag)
-87, List of Diagnos-
tic Trouble Code
(DTC).>

Go to step

CHECK AIR INTAKE SYSTEM.
1) Start and idle the engine.
2) Check the following items.
• Loose installation of intake manifold and
throttle body
• Cracks of intake manifold gasket and throttle
body gasket
• Disconnection of vacuum hoses

Is there any fault in air intake
system?

Repair air suction
and leaks.

Go to step

CHECK ELECTRONIC THROTTLE CON-
TROL.
1) Turn the ignition switch to OFF.
2) Remove the electronic throttle control.
<Ref. to FU(STI)-15, REMOVAL, Throttle
Body.> <Ref. to FU(w/o STI)-15, REMOVAL,
Throttle Body.>
3) Check the electronic throttle control.

Are foreign matter found inside
electronic throttle control?

Remove foreign
matter from elec-
tronic throttle con-
trol.