Subaru IMPREZA GD 2007 Series Manual page 256

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Diagnostic Procedure with Diagnostic Trouble Code (DTC)
AK:DTC P0172 SYSTEM TOO RICH (BANK 1)
DTC DETECTING CONDITION:
• Detected when two consecutive driving cycles with fault occur.
• GENERAL DESCRIPTION <Ref. to GD(H4SO)-78, DTC P0172 SYSTEM TOO RICH (BANK 1), Diagnos-
tic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
• Erroneous idling
• Engine stalls.
• Poor driving performance
CAUTION:
After repairing or replacing the defective parts, perform the Clear Memory Mode <Ref. to
EN(H4SO)(diag)-47, OPERATION, Clear Memory Mode.> and Inspection Mode <Ref. to EN(H4SO)(di-
ag)-38, PROCEDURE, Inspection Mode.>.
Step
1 CHECK EXHAUST SYSTEM.
2 CHECK AIR INTAKE SYSTEM.
3 CHECK FUEL PRESSURE.
WARNING:
Place "NO OPEN FLAMES" signs near the
working area.
CAUTION:
Be careful not to spill fuel.
Measure the fuel pressure. <Ref. to ME(H4SO)-
28, INSPECTION, Fuel Pressure.>
CAUTION:
Release fuel pressure before removing the
fuel pressure gauge.
4 CHECK ENGINE COOLANT TEMPERATURE
SENSOR.
1) Start the engine and warm-up completely.
2) Read the data of engine coolant tempera-
ture sensor signal using Subaru Select Monitor
or general scan tool.
NOTE:
• Subaru Select Monitor
For detailed operation procedures, refer to
"READ CURRENT DATA FOR ENGINE". <Ref.
to EN(H4SO)(diag)-32, Subaru Select Monitor.>
• General scan tool
For detailed operation procedure, refer to the
general scan tool operation manual.
Check
Are there holes or loose bolts
on exhaust system?
Are there holes, loose bolts or
disconnection of hose on air
intake system?
Is the measured value 339.5 —
360.5 kPa (3.5 — 3.7 kgf/cm
49 — 52 psi)?
Is the engine coolant tempera-
ture 75°C (167°F) or higher?
EN(H4SO)(diag)-147
ENGINE (DIAGNOSTICS)
Yes No
Repair the exhaust Go to step 2.
system.
Repair the air Go to step 3.
intake system.
Go to step 4.
Repair the follow-
2
, ing item.
Fuel pressure is
too high:
• Clogged fuel line
or bent hose
Fuel pressure is
too low:
• Improper fuel
pump discharge
• Clogged fuel line
Go to step 5. Replace the
engine coolant
temperature sen-
sor. <Ref. to
FU(H4SO)-22,
Engine Coolant
Temperature Sen-
sor.>