Subaru Legacy 2003 Service Manual page 572

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
25 GROUP OF #2 AND #4 CYLINDERS
Are there faults in #2 and #4 cylinders?
26 CYLINDER AT RANDOM
Is the engine idle unstable?
Value
There are faults.
Engine idle is unstable.
EN(H4SO)-175
ENGINE (DIAGNOSTICS)
Yes
Repair or replace Go to DTC P0171.
faulty parts. <Ref. to
EN(H4SO)-162,
NOTE:
DTC P0171 —
Check the follow-
SYSTEM TOO
ing items.
LEAN (BANK 1) —
• Spark plugs
, Diagnostic Pro-
• Fuel injectors
cedure with Diag-
• Compression
nostic Trouble
ratio
Code (DTC).>
• Skipping timing
belt teeth
Go to DTC P0171. Repair or replace
<Ref. to faulty parts.
EN(H4SO)-162,
NOTE:
DTC P0171 —
Check the follow-
SYSTEM TOO
ing items.
LEAN (BANK 1) —
• Spark plugs
, Diagnostic Pro-
• Fuel injectors
cedure with Diag-
• Compression
nostic Trouble
ratio
Code (DTC).>
No