Subaru 2002 IMPREZA Service Manual page 389

ENGINE LUBRICATION SYSTEM TROUBLE IN GENERAL
9. Engine Lubrication System Trouble in General
A: INSPECTION
Before performing diagnostics, make sure that the engine oil level is correct and no oil leakage exists.
Trouble
1. Warning light remains
on.
2. Warning light does
not go on.
3. Warning light flickers
momentarily.
Cracked diaphragm or oil leakage within switch
1) Oil pressure switch
failure
Broken spring or seized contacts
Clogged oil filter
Malfunction of oil by-pass valve of oil filter
Malfunction of oil relief valve of oil pump
2) Low oil pressure
Clogged oil passage
Excessive tip clearance and side clearance of oil
pump rotor and gear
Clogged oil strainer or broken pipe
Insufficient engine oil
3) No oil pressure Broken pipe of oil strainer
Stuck oil pump rotor
1) Burn-out bulb
2) Poor contact of switch contact points
3) Disconnection of wiring
1) Poor contact at terminals
2) Defective wiring harness
3) Low oil pressure
Possible cause
LU-25
LUBRICATION
Corrective action
Replace.
Replace.
Replace.
Clean or replace.
Clean or replace.
Clean.
Replace.
Clean or replace.
Replenish.
Replace.
Replace.
Replace.
Replace.
Repair.
Repair.
Repair.
Check for the same
possible causes as
listed in 1.—2).