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<h2>What is an engine thermostat?</h2>&nbsp;While all engines can become too hot, if your thermostat isn't working correctly, your engine's well-being is at serious risk. The engine thermostat, often simply referred to as a thermostat, regulates the engine's operating temperature within an optimal range (typically around 195 to 220 degrees Fahrenheit).<h2>How does a car thermostat work?</h2>As a temperature-sensitive valve within the cooling system, a car thermostat responds to changes in coolant temperature. Understanding how it works by the following breakdown steps:<ul><li>Closed position (cold start)</li></ul>Initially closed to help the engine warm up quickly.<ul><li>Heating up</li></ul>The engine generates heat during operation.<ul><li>Opening the thermostat</li></ul>A temperature-sensitive element (usually wax) causes the thermostat to open gradually.<ul><li>Coolant flow</li></ul>When open, coolant flows from the engine to the radiator.<ul><li>Maintaining optimal temperature</li></ul>Adjusts coolant flow to maintain the ideal engine temperature.<ul><li>Temperature regulation</li></ul>Continuously adjusts to prevent overheating and ensure efficient operation.<h2>Signs of a bad thermostat</h2><ol><li>Overheating: The engine becomes excessively hot due to a stuck-closed thermostat.</li><li>Low or fluctuating temperature: A thermostat stuck open results in a cooler engine, affecting fuel efficiency and heating.</li><li>Temperature warning light: Illuminates to indicate engine overheating due to a faulty thermostat.</li><li>Poor fuel efficiency: Stuck-open thermostat reduces fuel efficiency as the engine operates less efficiently at lower temperatures.</li><li>Inadequate cabin heating: Insufficient cabin heating in cold weather with a thermostat that's stuck open.</li><li>Coolant leaks: Gasket or sealing issues can lead to coolant leaks.</li><li>Rapid temperature fluctuations: The gauge shows rapid swings between hot and cold.</li><li>Engine running hot at idle: Higher engine temperature during idle or in traffic due to restricted coolant flow.</li><li>Slow or inconsistent warm-up: Longer-than-normal warm-up times, even in moderate weather.</li><li>Inconsistent heater operation: This affects the performance of the vehicle's heater, causing inconsistent or inadequate heating in cold weather.</li></ol>

Thermostat

Air Cleaner

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Air Filter Box

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Mass Air Flow Sensors/Car MAF Sensors | A-Premium

Air Flow Sensor

Air Intake Duct

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Air Intake Hose

Air Intake Manifold Actuator Control Solenoid

Air Intake Manifold Flap Adjuster

Air Intake Manifold Runner Control Sensor

Air Intake Resonator

Electric Vacuum Pump

Engine Air Duct Assembly

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Engine Air Filter

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Intake Manifold

Intake Manifold Flap Actuator

Intake Manifold Repair Bracket

Intake Manifold Runner Control Valve

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Intercooler

Intercooler Hose

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Oxygen Sensor

Car Oxygen Sensor Price From $24.99 | A-Premium

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Pressure Sensor

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Supercharger Pulley Drive Unit

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Supercharger Snout Rebuild Kit

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Throttle Body

Throttle Cable

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Throttle Position Sensor

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Turbocharger

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Turbocharger Gasket Kit

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Turbocharger Oil Line

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Vacuum Pump

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Air Filters & Intake Systems

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Camshaft Adjuster

Camshaft Adjuster Cover

Camshaft Kit

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Camshaft Timing Gear

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Camshafts

Chain Tensioner Adjuster

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Cylinder Head

Cylinder Head Assembly

Eccentric Shaft Actuator

Engine Timing Belt

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Engine Valve Cover

Engine Valve Cover Gasket

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Harmonic Balancer

Rocker Arm

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Rocker Arm Shaft Lifter Assembly

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Timing Belt Kit

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Timing Chain Gear

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Timing Chain Kit

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Timing Cover

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Timing-Control Valve Solenoid

Valve Cover Gasket

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Valve Lifter Guides

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Valve Lifters Tappet

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Cams, Timing & Valvetrain

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Belt Tensioner

Coolant Level Sensor

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Crank Installer Tool

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Crankcase Breather Hose

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Crankcase Breather Valve

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Crankshaft Position Sensor

Crankshaft Pulley

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Engine Oil Dipstick

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Engine Oil Dipstick Tube

Engine Oil Filter

Engine Oil Pan Gasket

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Flywheel

Harmonic Balancer Crankshaft Hub

Knock Sensor

Oil Baffle

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Oil Cooler

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Oil Cooler Line

Oil Drip Pan

Oil Filler Cap

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Oil Filter

Oil Filter Base

Oil Filter Cover

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Oil Filter Housing

Oil Filter Housing Cover

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Oil Level Sensor

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Oil Pan

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Oil Pump

Oil Pump Drive Gear Shaft

Oil Pump Pickup Tube

Oil Separator

Serpentine Belt

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Cranks, Pistons, Oil & Components

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Camshaft Position Sensor

Camshaft Position Sensor & Magnet Kit

Connector Plug

Distributor Cap

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Electronic Ignition System

Engine Valve Covers & Ignition Coils Kits

Glow Plug

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Glow Plug Relay Module

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Ignition Coil

Ignition Coils & Spark Plugs & Wires Kits

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Ignition Coils & Spark Plugs Kits

Ignition Coils & Wires Kits

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Ignition Distributor

Ignition Lock Cylinder

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Ignition Starter Switch

Ignition Switch Actuator

Kill Switch

Knock Detonation Sensor

Relay

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Spark Plug

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Spark Plug Wire

Electronic Control Modules, Ignition & Distributors

Engine Wiring Harness

Intake Manifold Repair Kit

Pulley

Engine Components & Accessories

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Active Grille Shutter Actuator

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Auxiliary Water Pump

Drive Motor Inverter Cooler

Electric Engine Water Pump

Engine Coolant Air Bleeder Valve

Engine Coolant Pipe

Engine Coolant Shut Off Valve

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Expansion Tank

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Expansion Tank Mounting Plate

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Fan Pulley Bracket

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Fuel Cooler

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Overflow Hose Connector

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Radiator

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Radiator Control Fan Module

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Radiator Core Support Skid Bar Plate

Radiator Fan Cooling Motor

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Radiator Hose

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Engine Cooling

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The engine comprises many essential elements such as the lower cylinder block, upper cylinder head(s), and the cooling & lubricating systems. With A-Premium aftermarket engine components, you can expect that your engine deliver years of reliable performance. We offer a diverse selection of engine components from air filters and ignition coils (kits) to fuel pumps to cater to your needs.

2003 Subaru Forester Thermostat

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