Subaru 2009 IMPREZA Service Manual page 579

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
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)-66, DTC P0172 SYSTEM TOO RICH (BANK 1), Diagnos-
tic Trouble Code (DTC) Detecting Criteria.>
TROUBLE SYMPTOM:
• Improper idling
• Engine stalls.
• Poor driving performance
CAUTION:
After servicing or replacing faulty parts, perform Clear Memory Mode <Ref. to EN(H4SO)(diag)-55,
OPERATION, Clear Memory Mode.>, and Inspection Mode <Ref. to EN(H4SO)(diag)-44, 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)-
27, 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)-34, Subaru Select Moni-
tor.>
• General scan tool
For detailed operation procedures, 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 333.4 —
360.5 kPa (3.4 — 3.7 kg/cm
48.4 — 52 psi)?
Is the engine coolant tempera-
ture 75°C (167°F) or higher?
EN(H4SO)(diag)-162
Yes
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)-25,
Engine Coolant
Temperature Sen-
sor.>
No