Subaru Impreza 2004 Service Manual page 126

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 CHECK ANY OTHER DTC ON DISPLAY.
2 CHECK IDLE AIR CONTROL SOLENOID
VALVE.
1)Turn the ignition switch to OFF.
2)Remove the idle air control solenoid valve
from throttle body. <Ref. to FU(H4DOTC)-36,
REMOVAL, Idle Air Control Solenoid Valve.>
3)Using an air gun, force air into the idle air
control solenoid valve by-pass air inlet. Con-
firm that forced air subsequently escapes from
both main air passage and assist air passage.
3 CHECK IDLE AIR CONTROL SOLENOID
VALVE DUTY RATIO.
1)Turn the ignition switch to ON.
2)Start the engine, and warm-up the engine.
3)Turn all accessory switches to OFF.
4)Read the data of idle air control solenoid
valve duty ratio using Subaru Select Monitor or
OBD-II general scan tool.
NOTE:
•Subaru Select Monitor
For detailed operation procedures, refer to the
"READ CURRENT DATA FOR ENGINE".
<Ref. to EN(H4DOTC)(diag)-32, Subaru
Select Monitor.>
•OBD-II general scan tool
For detailed operation procedures, refer to the
OBD-II General Scan Tool Instruction Manual.
4 CHECK BY-PASS AIR LINE.
1)Turn the ignition switch to OFF.
2)Remove the idle air control solenoid valve
from throttle body. <Ref. to FU(H4DOTC)-36,
REMOVAL, Idle Air Control Solenoid Valve.>
3)Remove the throttle body to intake manifold.
<Ref. to FU(H4DOTC)-13, REMOVAL, Throttle
Body.>
4)Using an air gun, force air into the solenoid
valve installation area and throttle valve inte-
rior. Confirm that forced air subsequently
escapes from both these areas.
Check
Is any other DTC displayed?
Does air flow out?
Is the duty ratio more than
60%?
Does air flow out?
EN(H4DOTC)(diag)-205
ENGINE (DIAGNOSTICS)
Yes
Inspect the rele- Go to step 2.
vant DTC using
"List of Diagnostic
Trouble Code
(DTC)". <Ref. to
EN(H4DOTC)(dia
g)-74, List of Diag-
nostic Trouble
Code (DTC).>
NOTE:
In this case, it is
not necessary to
inspect DTC
P0506.
Go to step 4. Replace the idle
air control solenoid
valve. <Ref. to
FU(H4DOTC)-36,
Idle Air Control
Solenoid Valve.>
After replace, Go
to step 3.
Go to step 4. END.
Replace the idle Replace the throt-
air control solenoid tle body. <Ref. to
valve. <Ref. to FU(H4DOTC)-13,
FU(H4DOTC)-36, Throttle Body.>
Idle Air Control
Solenoid Valve.>
No