Subaru Legacy 2004 Service Manual page 572

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
22 GROUP OF #1 AND #2 CYLINDERS
23 GROUP OF #3 AND #4 CYLINDERS
24 GROUP OF #1 AND #3 CYLINDERS
Check
Are there any faults in #1 and
#2 cylinders?
Are there any faults in #3 and
#4 cylinders?
Are there any faults in #1 and
#3 cylinders?
EN(H4SO 2.0)(diag)-140
Yes
Repair or replace Go to DTC P0171.
faulty parts. <Ref. to EN(H4SO
2.0)(diag)-126,
NOTE:
DTC P0171 SYS-
• Check the fol-
TEM TOO LEAN
lowing items.
(BANK 1), Diag-
• Spark plugs
nostic Procedure
• Fuel injectors
with Diagnostic
• Ignition coil
Trouble Code
• Compres-
(DTC).>
sion ratio
• If no abnormal is
discovered, check
for "IGNITION
CONTROL SYS-
TEM" of #1 and #2
cylinders side.
<Ref. to EN(H4SO
2.0)(diag)-58,
IGNITION CON-
TROL SYSTEM,
Diagnostics for
Engine Starting
Failure.>
Repair or replace Go to DTC P0171.
faulty parts. <Ref. to EN(H4SO
2.0)(diag)-126,
NOTE:
DTC P0171 SYS-
• Check the fol-
TEM TOO LEAN
lowing items.
(BANK 1), Diag-
• Spark plugs
nostic Procedure
• Fuel injectors
with Diagnostic
• Ignition coil
Trouble Code
• If no abnormal is
(DTC).>
discovered, check
for "16. D: IGNI-
TION CONTROL
SYSTEM" of #3
and #4 cylinders
side. <Ref. to
EN(H4SO
2.0)(diag)-58,
IGNITION CON-
TROL SYSTEM,
Diagnostics for
Engine Starting
Failure.>
Repair or replace Go to DTC P0171.
faulty parts. <Ref. to EN(H4SO
2.0)(diag)-126,
NOTE:
DTC P0171 SYS-
Check the follow-
TEM TOO LEAN
ing items.
(BANK 1), Diag-
• Spark plugs
nostic Procedure
• Fuel injectors
with Diagnostic
• Skipping timing
Trouble Code
belt teeth
(DTC).>
No