2004 Subaru WRX Emission Control

    • Bosch®Premium Oxygen Sensor
      $74.83from $59.86
      (0)
      Subaru WRX 2004, Premium Oxygen Sensor by Bosch®. Location: Downstream. A worn-out oxygen sensor can cause engine performance problems and shorten the life of the catalytic converter. Tune-up your vehicle with an Oxygen Sensor...
      Up to 15 % savings in fuel costsReduced CO2 emissions
      # 35994368
    • Bosch®Wideband Oxygen Sensor
      $152.38from $121.90
      (0)
      Subaru WRX 2004, Wideband Oxygen Sensor by Bosch®. Location: Upstream. This sensor utilizes a sophisticated sensing element enabling it to produce a precise output in proportion to the air/fuel ratio. The A/F sensor measures...
      Detects the exact amount of unburned fuel in the exhaust streamOE connectors and OE-style harness for continuous wire from connector to sensor
      # 35994378
    • Spectra Premium®Oxygen Sensor
      $118.90$95.12
      (0)
      Subaru WRX STI 2004, Oxygen Sensor by Spectra Premium®. Downstream. To ensure your vehicle has optimal performance and fuel economy while producing minimal emissions replace a defective O2 sensor with one backed by the...
      Increase vehicle fuel economy and engine performance while decreasing vehicle exhaust emissions100% performance tested to meet vehicle requirements
      # 22807971
    • Delphi®Oxygen Sensor
      $63.51from $50.81
      (0)
      Subaru WRX 2004, Oxygen Sensor by Delphi®, 7/8" Wrench, Square-4 Blade Connector, 18 x 1.5mm Thread, 4 Wires, 7/8" Wrench. As one of the leading suppliers of oxygen sensor technology since 1978, Delphi planar technology is the...
      OE connectors and wire lengths within three inches of OE specificationsResists high temperatures, vibration damage and wire corrosion to protect signal accuracy, and long life
      # 24591162
    • NTK®Replacement Oxygen Sensor
      $86.31$69.05
      (0)
      Subaru WRX 2004, Replacement Oxygen Sensor by NTK®. This product is designed to improve engine efficiency and fuel mileage, while reducing emissions and extending catalyst life. The oxygen sensor is made of premium quality material...
      Increases vehicle fuel economy and engine performance while decreasing vehicle exhaust emissionsDirect replacement
      # 22131767
    • Hitachi®Oxygen Sensor
      $211.90$169.52
      (0)
      Subaru WRX STI 2004, Oxygen Sensor by Hitachi®. This is an aftermarket part that replaces factory OE # 22690AA640. This sensor is manufactured using the latest electronic-sensing technology to ensure accurate measurement of the...
      Ensures precise measurement of exhaust gas oxygen contentMeets or exceeds OE specifications
      # 22063980
    • Denso®Downstream OE Connector Oxygen Sensor
      $59.05$47.24
      (0)
      Subaru WRX / WRX STI 2004, Downstream OE Connector Oxygen Sensor by Denso®, 1 Piece. Denso's light duty oxygen sensor started to appear on vehicles with the development of fuel injection systems. The basic job of the sensor is to...
      Corrosion-resistant stainless steel constructionPTFE filter blocks efficiency-robbing contaminants
      # 21104202
    • Bosch®Universal Fit Oxygen Sensor
      $47.03from $37.62
      (0)
      Subaru WRX 2004, Universal Fit Oxygen Sensor by Bosch®. Location: Downstream. Properly functioning oxygen sensors are important when it comes to your vehicle's fuel efficiency and reducing harmful exhaust emissions. That's why...
      Up to 15 % savings in fuel costsReduced CO2 emissions
      # 35994372
    • FRAM®PCV Valve
      $6.28$5.02
      (0)
      Subaru WRX FI 2004, PCV Valve by FRAM®. The Positive Crankcase Ventilation (PCV) system prevents the release of harmful emissions, helps keep engine oil clean and prevents excessive crankcase pressure, which can cause oil leaks....
      Essential component of the PCV systemRegulates flow of crankcase vapors into the engine
      # 40170785
    • Fel-Pro®EGR Valve Gasket
      $3.95$3.16
      (0)
      Subaru WRX 2.5L 2004, EGR Valve Gasket by Fel-Pro®. If you need durable gaskets to prevent leaks on your vehicle, Fel-Pro is the way to go. Engineered using the latest technologies and global engineering resources, the gaskets meet...
      Direct OEM replacement for a proper fitEnsure reliable sealing performance
      # 40581976
    • Accel®UEGO Wideband O2 Module
      $619.50$495.60
      (0)
      Universal UEGO Wideband O2 Module by Accel®. No matter what vehicle you own, its ignition system is what helps to achieve the mileage and power you bought it for. Quality ignition system components are a sure way to let your engine...
      The finest quality at a great priceImproves your engine's performance
      # 12710251
    • Accel®Gen VII™Linear Oxygen Sensor
      $93.53from $74.82
      (0)
      Universal Gen VII™Linear Oxygen Sensor by Accel®. No matter what vehicle you own, its ignition system is what helps to achieve the mileage and power you bought it for. Quality ignition system components are a sure way to let your...
      The finest quality at a great priceImproves your engine's performance
      # 12710299
    • Walker Products Inc.®OE Connector Oxygen Sensor
      $113.61$90.89
      (0)
      Subaru WRX 2004, OE Connector Oxygen Sensor by Walker Products Inc.®. Position: Rear. Is your CHECK ENGINE light on? Has your vehicle failed a state emissions test? Your vehicle’s emissions control system is in need of repair,...
      # 8739923
    • Genuine®Carbon Canister
      $152.76$122.21
      (0)
      Subaru WRX / WRX STI 2004, Carbon Canister by Genuine®. Is your CHECK ENGINE light on? Has your vehicle failed a state emissions test? Your vehicle’s emissions control system is in need of repair, but before you waste your time...
      # 8798136
    • Genuine®Purge Valve
      $59.39$47.51
      (0)
      Subaru WRX / WRX STI 2004, Purge Valve by Genuine®. Note: Located Next to Intake Manifold. Is your CHECK ENGINE light on? Has your vehicle failed a state emissions test? Your vehicle’s emissions control system is in need of...
      # 8804939
    • Genuine®EGR Vacuum Solenoid
      $214.39$171.51
      (0)
      Subaru WRX 2004, EGR Vacuum Solenoid by Genuine®. Position: Right. Also Known As Duty Solenoid. Is your CHECK ENGINE light on? Has your vehicle failed a state emissions test? Your vehicle’s emissions control system is in need of...
      # 44711906
    • Denso®Upstream OE Connector Air Fuel Ratio Sensor
      $124.75from $99.80
      (0)
      Subaru WRX 2004, Upstream OE Connector Air Fuel Ratio Sensor by Denso®, 1 Piece. The air/fuel ratio sensor sends information to the engine management computer to makes adjustments based on driving conditions. This wider range and...
      Tarnish-proof platinum electrodes provides longer life and maintains accuracyQuick-response planar zircon element can quickly detect oxygen concentration
      # 21104193
    • Genuine®PCV Valve
      $33.33$26.66
      (0)
      Subaru WRX STI 2004, PCV Valve by Genuine®. Note: Production: 04/2003. If you have a dirty air filter, clogged PCV valve, or defective MAF sensor you may be tempted to just run down to the local auto parts chain store for a...
      # 8801337
    • Genuine®Breather Hose
      $38.43from $30.74
      (0)
      Subaru WRX 2004, Breather Hose by Genuine®. Note: Right side Cylinder Head to P.C.V. Pipe. If you have a dirty air filter, clogged PCV valve, or defective MAF sensor you may be tempted to just run down to the local auto parts chain...
      # 8886383
    Guides & Articles
    An oxygen sensor (also known as an O2 sensor or Lambda sensor) is a sensor designed to generate a reading based on the content of oxygen in an automotive exhaust system. The sensor itself is made of a ceramic compound with porous-shaped electrodes coated in platinum, surrounded by a protective metal shell casing. O2 sensor casings are threaded, and the entire unit...
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