2004 Subaru WRX Emission Control

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    • (0 reviews)
      # 35994365
      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
      $60.71 - $67.13
    • (0 reviews)
      # 24136862
      Subaru WRX / WRX STI 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....
      Up to 15 % savings in fuel costsReduced CO2 emissions
      $38.59
    • (0 reviews)
      # 35994368
      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
      $118.95 - $172.59
    • (1 review)
      # 45000611
      Subaru WRX 2004, Downstream Oxygen Sensor by Standard®. SMP’s vision is to be the leading independent supplier to the automotive aftermarket, providing the highest quality products, competitive prices and the highest reputation...
      OE quality parts from top original equipment and aftermarket manufacturersFast shipping; 1-2 day delivery time regardless of where you’re located
      $54.80 - $73.65
    • (0 reviews)
      # 81776462
      Subaru WRX 2004, Oxygen Sensor by Delphi®. Connector Type: Square-4 Blade. Wrench Size: 7/8". As one of the leading suppliers of oxygen sensor technology since 1978, Delphi planar technology is the result of their OE and...
      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
      $59.64 - $181.06
    • (0 reviews)
      # 22063980
      Subaru WRX STI 2.5L 2004, Oxygen Sensor by Hitachi®. This sensor is manufactured using the latest electronic-sensing technology to ensure accurate measurement of the concentration of oxygen in the exhaust gas. It is constructed to...
      Ensures precise measurement of exhaust gas oxygen contentMeets or exceeds OE specifications
      $178.60
    • (0 reviews)
      # 21071902
      Subaru WRX / WRX STI 2004, Downstream OE Connector Oxygen Sensor by Denso®. Heated. Screw Type. 4 Wires, 21.26" / 54.00 cm Length. Denso's light duty oxygen sensor started to appear on vehicles with the development of fuel...
      Corrosion-resistant stainless steel constructionPTFE filter blocks efficiency-robbing contaminants
      $56.94
    • (0 reviews)
      # 21104193
      Subaru WRX 2004, Upstream OE Connector Air Fuel Ratio Sensor by Denso®. 4 Wires. 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
      $111.39 - $134.80
    • (0 reviews)
      # 95333064
      Subaru WRX 2004, Downstream Oxygen Sensor by Spectra Premium®. To ensure your vehicle has optimal performance and fuel economy while producing minimal emissions replace a defective O2 sensor with one backed by the aftermarket’s...
      Increase vehicle fuel economy and engine performance while decreasing vehicle exhaust emissions100% performance tested to meet vehicle requirements
      $51.83
    • (0 reviews)
      # 152247052
      Subaru WRX 2004, Downstream Oxygen Sensor by NTK®. Location: B1S2. OE Equivalent This product is designed to improve engine efficiency and fuel mileage, while reducing emissions and extending catalyst life. The oxygen sensor is...
      Increases vehicle fuel economy and engine performance while decreasing vehicle exhaust emissionsDirect replacement
      $72.33
    • (0 reviews)
      # 86086617
      Subaru WRX 2004, Professional™ Positive Crank Ventilation Valve by ACDelco®. Designed utilizing the latest technology, this product by ACDelco features premium quality and will perform better than advertised. Perfect for your...
      Designed to deliver trouble-free, consistent performanceRight for your vehicle and lifestyle
      $7.23
    • (0 reviews)
      # 8801306
      Subaru WRX STI 2.5L 2004, PCV Valve by Genuine®. Do you hear a humming or growling sound as you drive, or a clicking or clunking noise when cornering? If so, your vehicle may need wheel bearing or drive axle repairs. But before you...
      $24.05
    • (0 reviews)
      # 85013469
      Subaru WRX 2004, Air-Oil Separator by Moroso®. With this quality part backed by a great price, you can enjoy your vehicle so much more than you thought was possible. This Moroso part is specifically engineered to make your vehicle...
      Plumbed into a vehicle's PCV system to capture the excess crankcase vapors, residual oil mist and moisture from reentering the intake tractVehicles from the factory vent these excess crankcase vapors, residual oil mist and moisture right back into the intake manifold which could cause detonation, oil deposits to form in the intake tract including the valves themselves and from lowering the ficiency of the intercooler in intercooler equipped vehicles
      $292.76 - $356.11
    • (0 reviews)
      # 45113260
      Subaru WRX / WRX STI 2004, Intermotor™ Vapor Canister by Standard®. SMP’s vision is to be the leading independent supplier to the automotive aftermarket, providing the highest quality products, competitive prices and the...
      OE quality parts from top original equipment and aftermarket manufacturersFast shipping; 1-2 day delivery time regardless of where you’re located
      $82.81
    • (1 review)
      # 8798136
      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...
      $121.04
    • (1 review)
      # 88054855
      Subaru WRX 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 and gas...
      $121.04
    • (0 reviews)
      # 106171089
      Subaru WRX / WRX STI 2004, Rear Stainless Steel Small Oval Catalytic Converter by Walker®. Location: Rear. Catalytic Converter Substrate Material: Ceramic. CARB Compliant: No. Converter Configuration: Direct Fit. Converter Body...
      Designed to meet your vehicle’s specific emissions requirementsDirect fit replacement
      $77.18
    • (0 reviews)
      # 172053808
      Subaru WRX STI 2.5L 2004 Direct Fit Catalytic Converter by Eastern®. Outlet A: 2 Bolt Welded. If you need to replace your failed or damaged catalytic converter, this product is the right choice. Designed specifically for your...
      Direct OEM replacementConverts harmful engine emissions to less dangerous gases and water vapor
      $177.44 - $231.04
    • (0 reviews)
      # 172053797
      Subaru WRX 2004 Universal Fit Catalytic Converter by Eastern®. Whether your catalytic converter is damaged by road debris or failed due to an engine problem, you definitely need a new one, and this product is the way to go. Made of...
      Universal fitConverts harmful engine emissions to less dangerous gases and water vapor
      $46.62 - $90.49
    • (0 reviews)
      # 88880500
      Subaru WRX / WRX STI 2004, Catalytic Converter by Bosal®. Converter Configuration: Direct Fit. CARB Compliant: No. If you’re in need of a replacement catalytic converter, you can’t do better than Bosal. They’re a leading...
      Constructed to meet your vehicle’s specific emissions requirementsRadial flow concept allows for an even distribution of the gas flow in the converter for the optimal conversion of harmful gases
      $145.34 - $297.82
    • (0 reviews)
      # 86075000
      Subaru WRX / WRX STI 2.0L 2004, Catalytic Converter by DEC®. Converter Configuration: Direct Fit. Pick out a catalytic converter by DEC and get your emissions back into check without worrying to fail again. These catalytic...
      Direct fitMade from a heavy duty stainless steel outer shell
      $212.40 - $362.60
    • (0 reviews)
      # 86066730
      Subaru WRX / WRX STI 2.0L 2004, Rear Catalytic Converter and Pipe Assembly by DEC®. Includes: Pipe Assembly and O2 Sensor Port. Location: Rear. CARB Compliant: No. Converter Configuration: Direct Fit. Pick out a catalytic converter...
      Direct fitMade from a heavy duty stainless steel outer shell
      $205.03
    • (0 reviews)
      # 98837081
      Subaru WRX / WRX STI 2004, Dual Catch Can Kit by Radium®. Includes: 2x Black Anodized and Laser Engraved Billet Aluminum Catch Cans, 4x Black Anodized -AN Aluminum Adapter Fittings, 4x Black Anodized 90 Degree -AN Hose Ends, 1x...
      $427.45
    • (0 reviews)
      # 98137062
      Subaru WRX 2004, Direct Fit Federal OEM Grade Front Catalytic Converter with Header by MagnaFlow®. Catalytic Series: OEM Grade. Catalytic Converter Substrate Material: Ceramic. Converter Body Material: Stainless Steel. Location:...
      Reduces harmful emissionsIncreases exhaust flow compared to original factory converter
      $583.50
    • (0 reviews)
      # 61590407
      Subaru WRX 2004, Direct Fit Federal Standard Catalytic Converter by MagnaFlow®. Catalytic Series: Standard. Catalytic Converter Substrate Material: Ceramic. Converter Body Material: Stainless Steel. CARB Compliant: No. Converter...
      Converter body manufactured from heavy-duty stainless steelIncreases exhaust flow compared to original factory converter
      $320.31 - $485.43
    • (1 review)
      # 8804939
      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...
      $47.97
    • (1 review)
      # 88054864
      Subaru WRX 2004, Purge Valve 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 and gas running...
      $47.97
    • (0 reviews)
      # 45264031
      Subaru WRX 2004, Intermotor™ Vapor Canister Purge Solenoid by Standard®. SMP’s vision is to be the leading independent supplier to the automotive aftermarket, providing the highest quality products, competitive prices and the...
      OE quality parts from top original equipment and aftermarket manufacturersFast shipping; 1-2 day delivery time regardless of where you’re located
      $91.78 - $118.98
    • (0 reviews)
      # 45113557
      Subaru WRX / WRX STI 2004, Intermotor™ Vapor Canister Vent Solenoid by Standard®. SMP’s vision is to be the leading independent supplier to the automotive aftermarket, providing the highest quality products, competitive prices...
      OE quality parts from top original equipment and aftermarket manufacturersFast shipping; 1-2 day delivery time regardless of where you’re located
      $58.58
    • (0 reviews)
      # 155251375
      Subaru WRX / WRX STI 2.0L 2004, Vapor Canister Purge Valve by Dorman®. Dorman’s Vapor Canister Purge Valve restores on-board diagnosis of the EVAP system. Plus, its high quality metal and plastic construction keeps the system...
      Mounting hardware included (where applicable)O-ring included (where applicable)
      $104.34
    • (0 reviews)
      # 88054858
      Subaru WRX 2004, Passenger Side EGR Vacuum Solenoid 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...
      $136.75 - $173.21
    • (0 reviews)
      # 73693734
      Subaru WRX 2004, Air Oil Separator Kit by PERRIN Performance®. The PERRIN Performance Air Oil Separator traps oil from the crank case vents before it enters the intake, thus increasing intercooler efficiency and reduces chances of...
      Increases intercooler efficiencyReduces carbon build up
      $382.50
    • (0 reviews)
      # 8886383
      Subaru WRX 2004, Breather Hose by Genuine®. Do you hear a humming or growling sound as you drive, or a clicking or clunking noise when cornering? If so, your vehicle may need wheel bearing or drive axle repairs. But before you...
      OE quality parts from top original equipment and aftermarket manufacturersFast shipping; 1-2 day delivery time regardless of where you’re located
      $10.00 - $47.71
    • (0 reviews)
      # 8806395
      Subaru WRX / WRX STI Manufactured After January 01 / Manufactured Before March 31 2004, Crankcase O-Ring by Genuine®. Aluminium Washer For The Large Plugs On Crankcase. Is your CHECK ENGINE light on? Has your vehicle failed a state...
      OE quality parts from top original equipment and aftermarket manufacturersFast shipping; 1-2 day delivery time regardless of where you’re located
      $3.24
    • (0 reviews)
      # 18907543
      Subaru WRX STI 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...
      Direct OEM replacement for a proper fitEnsure reliable sealing performance
      $3.06
    • (0 reviews)
      # mpn358583092
      Universal Air-Oil Separator PCV Delete Kit by Moroso®. With this quality part backed by a great price, you can enjoy your vehicle so much more than you thought was possible. This Moroso part is specifically engineered to make your...
      $98.86
    • (0 reviews)
      # mpn2059757184
      Universal Clamp On Dry Sump Breather Tank by JOES Racing®. Size: 1"-1/2". JOES Dry Sump Breather tank is designed to allow venting of your dry sump tank while catching any oil that blows out. It’s a compact 3" x 3" x 6.5" to fit...
      Designed to deliver trouble-free, consistent performanceRight for your vehicle and lifestyle
      $89.81
    • (1 review)
      # 139379692
      Universal Bullet Catalytic Converters by Eastern®. Whether your catalytic converter is damaged by road debris or failed due to an engine problem, you definitely need a new one, and this product is the way to go. Made of stainless...
      Universal fitConverts harmful engine emissions to less dangerous gases and water vapor
      $66.16 - $100.28
    • (0 reviews)
      # 139379691
      Universal Eco GM Round Catalytic Converter by Eastern®. Overall Length: 16". Converter Body Length: 12". Keep your exhaust emissions within specifications and your vehicle running in top condition with this quality product. Made of...
      Universal fitConverts harmful engine emissions to less dangerous gases and water vapor
      $83.88 - $88.78
    • (0 reviews)
      # 172044678
      Universal Large Oval Catalytic Converter by Eastern®. Overall Length: 16". Converter Body Length: 12". Keep your exhaust emissions within specifications and your vehicle running in top condition with this quality product. Made of...
      Universal fitConverts harmful engine emissions to less dangerous gases and water vapor
      $72.25 - $117.90
    • (0 reviews)
      # 139371691
      Universal Large Oval Dual Inlet Catalytic Converter by Eastern®. Outlet A: 2". Keep your exhaust emissions within specifications and your vehicle running in top condition with this quality product. Made of stainless steel, the...
      Universal fitConverts harmful engine emissions to less dangerous gases and water vapor
      $70.86 - $143.46
    • (0 reviews)
      # 172044684
      Universal Large Oval Single Inlet Catalytic Converter by Eastern®. Keep your exhaust emissions within specifications and your vehicle running in top condition with this quality product. Made of stainless steel, the catalytic...
      Universal fitConverts harmful engine emissions to less dangerous gases and water vapor
      $83.94 - $100.94
    • (0 reviews)
      # 139371686
      Universal Oval Body Catalytic Converter by Eastern®. Keep your exhaust emissions within specifications and your vehicle running in top condition with this quality product. Made of stainless steel, the catalytic converter is...
      Universal fitConverts harmful engine emissions to less dangerous gases and water vapor
      $45.48 - $108.03
    • (0 reviews)
      # 139371692
      Universal QuieCat™ Oval Resonated Converter by Eastern®. Overall Length: 18". Converter Body Length: 14". The new Eastern Catalytic QuietCat™ converter is specifically designed to meet the demand for quieter operation on full...
      Baffled tube reduces sound levels by 35% without losing horsepowerHigh flow design retains maximum engine output and maximizes catalytic efficiency
      $61.60 - $109.69
    • (0 reviews)
      # 139371685
      Universal Round Body Catalytic Converter by Eastern®. Keep your exhaust emissions within specifications and your vehicle running in top condition with this quality product. Made of stainless steel, the catalytic converter is...
      Universal fitConverts harmful engine emissions to less dangerous gases and water vapor
      $42.50 - $89.96
    • (0 reviews)
      # 172044711
      Universal Stuffed Tube Catalytic Converter with EndCap by Eastern®. Keep your exhaust emissions within specifications and your vehicle running in top condition with this quality product. Made of stainless steel, the catalytic...
      Universal fitConverts harmful engine emissions to less dangerous gases and water vapor
      $49.63 - $80.91
    • (0 reviews)
      # 139371684
      Universal Universal Fit Catalytic Converter by Eastern®. Whether your catalytic converter is damaged by road debris or failed due to an engine problem, you definitely need a new one, and this product is the way to go. Made of...
      Universal fitConverts harmful engine emissions to less dangerous gases and water vapor
      $55.42 - $84.21
    • (0 reviews)
      # 174563966
      Universal Catalytic Converter by Bosal®. Converter Configuration: Universal Fit. If you’re in need of a replacement catalytic converter, you can’t do better than Bosal. They’re a leading supplier to vehicle manufacturers and...
      Constructed to meet your vehicle’s specific emissions requirementsRadial flow concept allows for an even distribution of the gas flow in the converter for the optimal conversion of harmful gases
      $70.91 - $71.91
    • (0 reviews)
      # 182090567
      Universal Catalytic Converter by Bosal®. Converter Configuration: Direct Fit. CARB Compliant: No. If you’re in need of a replacement catalytic converter, you can’t do better than Bosal. They’re a leading supplier to vehicle...
      Constructed to meet your vehicle’s specific emissions requirementsRadial flow concept allows for an even distribution of the gas flow in the converter for the optimal conversion of harmful gases
      $53.39 - $112.81
    • (0 reviews)
      # 107663259
      Universal Oxygen Sensor by K&N®. Protect your expensive racing engine and keep it running at peak performance with these Fuel Injection Line Air Filters. They’ll keep the injector nozzle aeration holes from ingesting dirt or...
      $13.93 - $90.99
    • (0 reviews)
      # mpn1589831653
      Harness by Fast®. Includes Wide-Band Sensor and Harness to convert a a Single Sensor Wideband Unit to a Dual Sensor Unit. Also includes weld in O2 bung and a plug for it.
      High quality at an affordable priceExpertly made from premium materials
      $133.16
    • (7 reviews)
      # 152045176
      Universal Aluminum Oil Catch Tank by Weapon-R®. Whether you’re going racing or just want to look like you are, this aluminum tank will dress up your engine compartment.
      Manufactured from Billet 6061 AluminumBillet Aluminum machined fittings
      $59.50 - $128.00
    • (7 reviews)
      # 152045214
      Universal Neo-Ti Aluminum Oil Catch Tank by Weapon-R®. Whether you’re going racing or just want to look like you are, this Neo-Titanium Finish aluminum tank will dress up your engine compartment.
      Manufactured from Billet 6061 AluminumBillet Aluminum machined fittings
      $89.25
    • (1 review)
      # 107662222
      Universal Clamp On Crankcase Vent Filter by K&N®. Designed utilizing the latest technology, this Crankcase Vent Filter by K&N features premium quality and will perform better than advertised. Perfect for your vehicle and lifestyle,...
      Designed to deliver trouble-free, consistent performanceRight for your vehicle and lifestyle
      $19.69 - $23.35
    • (1 review)
      # 107662290
      Universal Push On Crankcase Vent Filter by K&N®. Designed utilizing the latest technology, this Crankcase Vent Filter by K&N features premium quality and will perform better than advertised. Perfect for your vehicle and lifestyle,...
      Designed to deliver trouble-free, consistent performanceRight for your vehicle and lifestyle
      $9.42 - $92.99
    • (0 reviews)
      # mpn753352631
      Universal Crankcase Evacuation System by BTP®. Designed utilizing the latest technology, this product delivers the performance you've been looking for. With this second-to-none part by BTP you will keep emission control system in...
      Designed for better performance of your emission control systemRight for your vehicle and lifestyle
      $34.74
    • (1 review)
      # mpn753352945
      Universal Polished Aluminum PCV Valve by BTP®. 3/4" O.D. Neck. 3/8" Tube. Designed utilizing the latest technology, this product delivers the performance you've been looking for. With this second-to-none part by BTP you will keep...
      Designed for better performance of your emission control systemRight for your vehicle and lifestyle
      $20.07
    • (0 reviews)
      # 118615091
      Universal Oil Catch Can by Vibrant Performance®. Vibrant Performance offers the most versatile Universal Catch Cans on the market. Made entirely from T6061 Aluminum, it is suitable for various types of service: Oil, Fluid (i.e....
      Top End Cap is pressure fitEach End Cap also features a port tapped for 3/4” NPT fittings, perfect for running a breather filter off your Catch Can
      $102.38
    • (0 reviews)
      # 118569120
      Universal Round Straight Breather Air Filter by Spectre Performance®. Filter Material: Non-woven Synthetic. Top Material/Finish: Chrome. Rooted in racing, Spectre Performance designs and builds every product with the same goal in...
      High-tech engine parts for the most power and best performanceThe finest exterior and interior parts for superior appearance and functionality
      $10.86 - $18.25
    • (0 reviews)
      # 118569184
      Universal Clamp-On Style Mini Breather Filter by Spectre Performance®. Flange Inside Diameter: 0.375" (10 mm). Flange Length: 0.75" (19 mm). Height: 1.75" (44 mm). Outside Diameter: 2" (51 mm). Top Material/Finish: Chrome. Top...
      High-tech engine parts for the most power and best performanceThe finest exterior and interior parts for superior appearance and functionality
      $9.80 - $13.73




    Guides & Articles

    • Replacement Emission Control Parts
      Oxygen Sensors - Why Does My Car Have Four, And Can I Replace One Myself?
      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 is designed to screw in until it reaches a half-in, half-out position on the exhaust pipe. Modern oxygen sensors are heated to ensure they reach operating temperature quickly.
    • Ignition Parts
      Auto Parts: Dealer vs. Aftermarket
      The question of whether to buy parts from an automotive dealer vs. ones from aftermarket manufacturers is as age-old as the automobile itself. Below, we'll take a look at things worth considering to help you make a better choice if you're facing that same question. Automobile manufacturers and dealerships always advertise the fact that their parts are "genuine" because they were made by the exact same production facility that made the parts installed on the assembly line.

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    2004 Subaru WRX Emission Control Reviews

    Average rating:  4.5  4.5 - 2 reviews
    4.8 of 5
    Good Purchase
    Recently I have mounted new cat. My purchase has a faultless casing and everything measures up perfectly. That's nice deal for my Dodge, because the sound great. I like the tonality of these high flow catalytic if your looking for high flow cats these are the way to go.
    CPosted by Craig Walters (Louisbourg, NS) /
    Was this review helpful for you? Yes
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    2004 Subaru WRX Models
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