Subaru Legacy 2004 Service Manual page 573

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
25 GROUP OF #2 AND #4 CYLINDERS
26 CYLINDER AT RANDOM
Check
Are there any faults in #2 and
#4 cylinders?
Is the engine idle rough?
EN(H4SO 2.0)(diag)-141
ENGINE (DIAGNOSTICS)
Yes
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
• Compression
Trouble Code
ratio
(DTC).>
• Skipping timing
belt teeth
Go to DTC P0170. Repair or replace
<Ref. to EN(H4SO faulty parts.
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
• Compression
Trouble Code
ratio
(DTC).>
No