Subaru 2009 IMPREZA Service Manual page 1399

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
ENGINE (DIAGNOSTICS)
Step
23 GROUP OF #1 AND #3 CYLINDERS.
24 GROUP OF #2 AND #4 CYLINDERS.
25 CYLINDER AT RANDOM.
Check
Are there any faults in #1 and
#3 cylinders?
Are there any faults in #2 and
#4 cylinders?
Is the engine idle rough?
EN(H4DOTC)(diag)-178
Yes No
Repair or replace Go to DTC P0171.
faulty parts. <Ref. to
EN(H4DOTC)(diag)
NOTE:
-151, DTC P0171
Check the follow-
SYSTEM TOO
ing items.
LEAN (BANK 1),
• Spark plug
Diagnostic Proce-
• Fuel injector
dure with Diagnos-
• Compression ra-
tic Trouble Code
tio
(DTC).>
• Skipping timing
belt teeth
Repair or replace Go to DTC P0171.
faulty parts. <Ref. to
EN(H4DOTC)(diag)
NOTE:
-151, DTC P0171
Check the follow-
SYSTEM TOO
ing items.
LEAN (BANK 1),
• Spark plug
Diagnostic Proce-
• Fuel injector
dure with Diagnos-
• Compression ra-
tic Trouble Code
tio
(DTC).>
• Skipping timing
belt teeth
Go to DTC P0171. Repair or replace
<Ref. to faulty parts.
EN(H4DOTC)(diag)
NOTE:
-151, DTC P0171
Check the follow-
SYSTEM TOO
ing items.
LEAN (BANK 1),
• Spark plug
Diagnostic Proce-
• Fuel injector
dure with Diagnos-
• Compression ra-
tic Trouble Code
tio
(DTC).>