Subaru IMPREZA 2004 Service Manual page 119

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
1 CHECK ANY OTHER DTC ON DISPLAY.
2 CHECK AIR INTAKE SYSTEM.
1)Turn the ignition switch to ON.
2)Start the 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
3 CHECK THROTTLE CABLE.
4 CHECK AIR BY-PASS LINE.
1)Turn the ignition switch to OFF.
2)Remove the idle air control solenoid valve
from throttle body. <Ref. to FU(H4SO)-35, Idle
Air Control Solenoid Valve.>
3)Confirm that there are no foreign particles in
air by-pass line.
BA:DTC P0558 GENERATOR CIRCUIT LOW INPUT
CAUTION:
For diagnostic procedure, refer to DTC P0559. <Ref. to EN(H4SO)(diag)-197, DTC P0559 GENERATOR
CIRCUIT HIGH INPUT, Diagnostic Procedure with Diagnostic Trouble Code (DTC).>.
Check
Is any other DTC displayed?
Is there a fault in air intake sys-
tem?
Is throttle cable play correct?
Is air by-pass line clogged by
foreign particles?
EN(H4SO)(diag)-196
Yes
Inspect DTC using Go to step 2.
"List of Diagnostic
Trouble Code
(DTC)". <Ref. to
EN(H4SO)(diag)-
74, List of Diag-
nostic Trouble
Code (DTC).>
NOTE:
In this case, it is
not necessary to
inspect
DTC P0519.
Repair air suction Go to step 3.
and leaks.
Go to step 4. Adjust throttle
cable. <Ref. to
SP(H4SO)-9,
INSTALLATION,
Accelerator Con-
trol Cable.>
Remove foreign Replace the idle
particles from air air control solenoid
by-pass line. valve. <Ref. to
FU(H4SO)-35, Idle
Air Control Sole-
noid Valve.>
No