Subaru Impreza 2004 Service Manual page 83

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
16 CHECK CYLINDER.
Check
Is there a fault in that cylinder? Repair or replace
EN(H4DOTC)(diag)-162
Yes
Go to DTC P0171
the faulty parts. and P0172. <Ref.
to
NOTE:
EN(H4DOTC)(dia
Check the follow-
g)-143, DTC
ing items.
P0171 SYSTEM
• Spark plug
TOO LEAN (BANK
• Fuel injector
1), Diagnostic Pro-
• Compression
cedure with Diag-
pressure
nostic Trouble
Code (DTC).>
No