Subaru 2002 IMPREZA Service Manual page 1340

DIAGNOSTIC PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ENGINE (DIAGNOSTICS)
Step
23 GROUP OF #3 AND #4 CYLINDERS
24 GROUP OF #1 AND #3 CYLINDERS
25 GROUP OF #2 AND #4 CYLINDERS
26 CYLINDER AT RANDOM
Check
Are there faults in #3 and #4
cylinders?
Are there faults in #1 and #3
cylinders?
Are there faults in #2 and #4
cylinders?
Is the engine idle rough?
EN(TURBO)-180
Yes
Repair or replace Go to DTC P0171
the faulty parts. and P0172. <Ref.
to EN(TURBO)-
NOTE:
158, DTC P0171
• Check the fol-
— FUEL TRIM
lowing items.
MALFUNCTION
• Spark plugs
(A/F TOO LEAN)
• Fuel injectors
—, Diagnostic Pro-
• Ignition coil
cedure with Diag-
• If no abnormal is
nostic Trouble
discovered, check
Code (DTC).>
for "16. D: IGNI-
TION CONTROL
SYSTEM" of #3
and #4 cylinders
side. <Ref. to
EN(TURBO)-66,
Ignition Control
System.>
Repair or replace Go to DTC P0171
the faulty parts. and P0172. <Ref.
to EN(TURBO)-
NOTE:
158, DTC P0171
Check the follow-
— FUEL TRIM
ing items.
MALFUNCTION
• Spark plugs
(A/F TOO LEAN)
• Fuel injectors
—, Diagnostic Pro-
• Skipping timing
cedure with Diag-
belt teeth
nostic Trouble
Code (DTC).>
Repair or replace Go to DTC P0171
the faulty parts. and P0172. <Ref.
to EN(TURBO)-
NOTE:
158, DTC P0171
Check the follow-
— FUEL TRIM
ing items.
MALFUNCTION
• Spark plugs
(A/F TOO LEAN)
• Fuel injectors
—, Diagnostic Pro-
• Compression
cedure with Diag-
ratio
nostic Trouble
• Skipping timing
Code (DTC).>
belt teeth
Go to DTC P0171 Repair or replace
and P0172. <Ref. the faulty parts.
to EN(TURBO)-
NOTE:
158, DTC P0171
Check the follow-
— FUEL TRIM
ing items.
MALFUNCTION
• Spark plugs
(A/F TOO LEAN)
• Fuel injectors
—, Diagnostic Pro-
• Compression
cedure with Diag-
ratio
nostic Trouble
Code (DTC).>
No