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<h2>What does the O2 sensor do in a car?</h2>
You can find an oxygen (O2) sensor in your vehicle's exhaust system. It looks similar to a <a href="https://a-premium.com/spark-plug">spark plug</a> and is the same size. It ensures that the oxygen in your car&rsquo;s engine or the air-fuel ratio is optimal. The oxygen sensor exists in two different settings concerning the converter. You can arrange it before the converter or after the converter. Setting it before the converter is called upstream, and setting it after the converter is called downstream. The oxygen sensor gets its data and communicates within the system with the help of an electrical signal or a voltage signal. It sends the data to the central computer located in the engine, and the computer ensures that the mixture of oxygen and fuel is in optimal amounts to keep the engine running in top condition.
The oxygen sensors in your car are not such an item that they need to be replaced regularly without any issue. Unlike the air filters or the oil in your car, you only have to replace the oxygen sensors when they malfunction. If the oxygen sensor fails and does not work properly, the vehicle won't be able to correctly tell the ratio of air and fuel, which can also lead to excessive emissions from the vehicle. This failure to work seamlessly can also damage other components of your car, such as the <a href="https://a-premium.com/catalytic-converter">catalytic converter</a>.
<h2>How to tell a faulty O2 sensor?</h2>
When an&nbsp; O2 sensor in a vehicle becomes faulty or deteriorates, it can exhibit several symptoms including:
<ol>
<li>Increased emissions: Higher pollution output, potential emission test failure.</li>
<li>Check engine light: Illuminates when o2 sensor trouble codes are detected.</li>
<li>Rough idling: Unsteady engine idling and occasional stalling.</li>
<li>Failed emissions test: The vehicle may not pass emissions testing.</li>
<li>Delayed engine response: Slower acceleration when pressing the gas pedal.</li>
<li>Excessive fuel consumption: Increased fuel usage, resulting in higher costs.</li>
</ol>

Oxygen Sensor

Car Oxygen Sensor Price From $24.99 | A-Premium

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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

Electric Vacuum Pump

Engine Air Duct Assembly

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Engine Air Filter

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Intake Manifold

Intake Manifold Flap Actuator

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Intercooler

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Pressure Sensor

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Throttle Body

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Throttle Position Sensor

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Turbocharger

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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

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Camshaft Timing Gear

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Camshafts

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Engine Valve Cover

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Harmonic Balancer

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Timing Belt Kit

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Timing Chain Kit

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Timing Cover

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Timing-Control Valve Solenoid

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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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Crankcase Breather Hose

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Crankcase Breather Valve

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Crankshaft Position Sensor

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Engine Oil Dipstick Tube

Engine Oil Filter

Engine Oil Pan Gasket

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Flywheel

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Oil Cooler

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Oil Cooler Line

Oil Filler Cap

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Oil Filter

Oil Filter Base

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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

Cranks, Pistons, Oil & Components

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Camshaft Position Sensor

Camshaft Position Sensor & Magnet Kit

Connector Plug

Distributor Cap

Engine Valve Covers & Ignition Coils Kits

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Glow Plug Relay Module

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Ignition Coil

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Ignition Coils & Spark Plugs Kits

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Ignition Distributor

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Ignition Starter Switch

Ignition Switch Actuator

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

Engine Components & Accessories

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Auxiliary Water Pump

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Expansion Tank

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Expansion Tank Mounting Plate

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Fuel Cooler

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Radiator

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Radiator Hose

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Radiator Support Assembly

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Temperature Sensor

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Turbo Hose

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Water Coolant Pipe

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Water Outlet

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Engine Cooling

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Engine Mount

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Engine Mounts

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Catalytic Converter

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EGR Valve

Emissions Fluid Pump

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Exhaust Fluid Heater

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Exhaust Gas Temperature Sensor

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Exhaust Manifold

Fuel Tank Breather Valve

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Fuel Vapor Leak Detection Pump

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Nitrogen Oxide Sensor

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Secondary Air Injection Check Valve

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Vapor Canister Vent Solenoid

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Exhaust & Emission Systems

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Fuel Filter

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Fuel Injection Control Module

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Fuel Injection Pressure Regulator

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Fuel Injector

Fuel Injector Kit

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Fuel Injector Module Wiring Harness

Fuel Line Kit

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Fuel Pump

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Fuel Sending Unit

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Fuel Tank Filler Neck Pipe

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Fuel Tank Strap

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High Pressure Fuel Pump

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Idle Air Control Valve

Mechanical Fuel Pump

Oil Pressure Relief Valve

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Fuel Systems & Components

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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.

2009 Subaru Legacy Oxygen Sensor

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