Subaru Impreza 2004 - Engine Lubrication System Trouble in General

LU(H4SO)-21
LUBRICATION
Engine Lubrication System Trouble in General
8. Engine Lubrication System Trouble in General
A: INSPECTION
Before performing diagnostics, make sure the engine oil level is correct and no oil leakage exists.
Trouble Possible cause Corrective action
1. Warning light remains
on.
1) Oil pressure switch
failure
Cracked diaphragm or oil leakage within switch Replace.
Broken spring or seized contacts Replace.
2) Low oil pressure
Clogged oil filter Replace.
Malfunction of oil by-pass valve of oil filter Clean or replace.
Malfunction of oil relief valve of oil pump Clean or replace.
Clogged oil passage Clean.
Excessive tip clearance and side clearance of oil
pump rotor and gear
Replace.
Clogged oil strainer or broken pipe Clean or replace.
3) No oil pressure
Insufficient engine oil Replenish.
Broken pipe of oil strainer Replace.
Stuck oil pump rotor Replace.
2. Warning light does
not go on.
1) Malfunction of combination meter Replace.
2) Poor contact of switch contact points Replace.
3) Disconnection of wiring Repair.
3. Warning light flickers
momentarily.
1) Poor contact at terminals Repair.
2) Defective wiring harness Repair.
3) Low oil pressure
Check for the same
possible causes as
listed in 1.—2).