Subaru LEGACY 2004 Service Manual page 174

Symptom
10. Excessive fuel consump-
tion
Engine Trouble in General
Problem parts, etc.
Engine control system <Ref. to EN(H4SO 2.0)(diag)-2, Basic Diagnostic Procedure.>
Intake system
Belt
Compression
Lubrication system
Cooling system
ME(H4SO 2.0)-87
Possible cause
Dirty air cleaner element
Defective timing
Incorrect valve clearance
Loosened spark plug or defective gasket
Loosened cylinder head bolt or defective gasket
Improper valve sealing
Defective valve stem
Worn or broken valve spring
Worn or stuck piston rings, cylinder and piston
Incorrect valve timing
Incorrect oil pressure
Over-cooling
MECHANICAL
RANK
A
A
B
B
C
C
B
C
C
B
B
C
C