Subaru Legacy 2003 Service Manual page 894

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
8 CHECK AIR INTAKE SYSTEM.
1) Turn ignition switch to ON.
2) Start engine, and idle it.
3) Check the following items.
• Loose installation of intake manifold, idle air
control solenoid valve and throttle body
• Cracks of intake manifold gasket, idle air con-
trol solenoid valve gasket and throttle body
gasket
• Disconnections of vacuum hoses
Is there a fault in air intake system?
9 CHECK AIR BY-PASS LINE.
1) Turn ignition switch to OFF.
2) Remove idle air control solenoid valve from
throttle body. <Ref. to FU(H4SOw/oOBD)-
33, Idle Air Control Solenoid Valve.>
3) Confirm that there are no foreign particles
in by-pass air line.
Are foreign particles in by-pass air line?
10 CHECK AIR BY-PASS LINE.
1) Turn ignition switch to OFF.
2) Remove idle air control solenoid valve from
throttle body. <Ref. to FU(H4SOw/oOBD)-
33, Idle Air Control Solenoid Valve.>
3) Remove throttle body from intake mani-
fold. <Ref. to FU(H4SOw/oOBD)-13,
Throttle Body.>
4) Confirm that there are no foreign particles
in the throttle body.
5) Using an air gun, force air into idle air con-
trol solenoid valve installation area. Confirm
that forced air subsequently escapes from
throttle body interior.
Does air flow out?
Value
The system is faulty.
Foreign particles in by-pass air
line.
Air flows out.
EN(H4SOw/oOBD)-75
ENGINE (DIAGNOSTICS)
Yes
Repair air suction Go to step 9.
and leaks.
Remove foreign Replace idle air
particles from by- control solenoid
pass air line. valve. <Ref. to
FU(H4SOw/
oOBD)-33, Idle Air
Control Solenoid
Valve.>
Replace idle air Replace throttle
control solenoid body. <Ref. to
valve. <Ref. to FU(H4SOw/
FU(H4SOw/ oOBD)-13, Throt-
oOBD)-33, Idle Air tle Body.>
Control Solenoid
Valve.>
No