Subaru Legacy 2002 Service Manual page 810

Symptom
7. Spark knock
8. After burning in exhaust system
*1: Check ignition coil & ignitor assembly and spark plug.
*2: Indicate the symptom occurring only in cold temperatures.
*3: Ensure the secure installation.
*4: Check fuel injector, fuel pressure regulator and fuel filter.
*5: Inspect air leak in air intake system.
*6: Adjust accelerator cable.
2. AUTOMATIC TRANSMISSION
NOTE:
Check general diagnostics table with non-conformity symptom for automatic transmission. <Ref. to AT-2,
Basic Diagnostic Procedure.>
GENERAL DIAGNOSTIC TABLE
Problem parts
1) Intake manifold pressure sensor
2) Intake air temperature sensor
3) Intake air temperature and pressure sensor
4) Engine coolant temperature sensor
5) Knock sensor
6) Fuel injection parts (*4)
7) Fuel pump and fuel pump relay
1) Intake manifold pressure sensor
2) Intake air temperature sensor
3) Intake air temperature and pressure sensor
4) Engine coolant temperature sensor (*2)
5) Fuel injection parts (*4)
6) Fuel pump and fuel pump relay
S078257A1002
EN-293
Engine (Diagnostics)