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K&N 33-2231 High Performance Replacement Air Filter

by K&N
4.7 out of 5 stars 58 customer reviews

Price: $48.99 & FREE Shipping on orders over $49. Details
In Stock.
Ships from and sold by Amazon.com.
  • Enter your model number above to make sure this fits.
  • Designed to boost horsepower and rate of acceleration
  • Can be cleaned and used again
  • High air flow with exceptional filtration
  • Lasts up to 50,000 miles before cleaning is required depending on driving conditions
  • Works with original equipment manufacturer vehicle electronics
68 new from $48.99 1 used from $39.19
$48.99 & FREE Shipping on orders over $49. Details In Stock. Ships from and sold by Amazon.com.

Frequently Bought Together

  • K&N 33-2231 High Performance Replacement Air Filter
  • +
  • Mann-Filter CUK 6724 Cabin Filter With Activated Charcoal for select BMW models
  • +
  • Mann-Filter HU 925/4 X Metal-Free Oil Filter
Total price: $79.38
Buy the selected items together


Product Information

Technical Details

Brand K&N
Item Weight 12.3 ounces
Product Dimensions 9.9 x 7.6 x 1.8 inches
Origin China
Item model number 33-2231
Manufacturer Part Number 33-2231
OEM Part Number 33-2231

Technical Specification

Additional Information

ASIN B000630290
Customer Reviews
4.7 out of 5 stars 58 customer reviews

4.7 out of 5 stars
Best Sellers Rank #113,732 in Automotive (See top 100)
#1,620 in Automotive > Replacement Parts > Filters > Air Filters & Accessories > Air Filters
Shipping Weight 14.4 ounces (View shipping rates and policies)
Domestic Shipping Currently, item can be shipped only within the U.S. and to APO/FPO addresses. For APO/FPO shipments, please check with the manufacturer regarding warranty and support issues.
International Shipping This item is not eligible for international shipping. Learn More
Date First Available February 10, 2005

Warranty & Support

Warranty, Parts:PartsWarranty, Labor:The manufacturer may be liable if the product suffers technical failure, but not if the purchaser damages the product through his own actions.
Manufacturer’s warranty can be requested from customer service. Click here to make a request to customer service.

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Product Description

K&N's replacement air filters are designed to increase horsepower and acceleration while providing excellent filtration. We make over 1,200 different replacement air filters for virtually every vehicle on the road. These filters are washable and reusable and are custom designed to fit into your existing factory air box. Their drop-in design means adding performance is simple. With most vehicles you simply remove the disposable air filter and replace it with a K&N. See applicable instruction sheet for details. Our stock replacement air filters for street vehicles are covered by our famous K&N Million-Mile Limited Warranty and will be THE LAST AIR FILTER YOUR VEHICLE WILL EVER NEED.

From the Manufacturer

Also available: K&N Cabin Air Filters

The K&N Washable Cabin Air Filter is the first of its kind designed to replace your vehicle's stock cabin air filter with a washable and reusable version that cleans and freshens incoming air. K&N Cabin Air Filters are designed to be cleaned and reused over and over again. Using a combination of an advanced synthetic filter media and K&N Refresher spray, the K&N Washable Cabin Air Filter grabs and holds dust particles.

Cabin Air Filters

Oil Filters

Intake Systems

Recharger Kits


Customer Questions & Answers

Customer Reviews

Top Customer Reviews

Verified Purchase
I've had this product on a 2004 BMW 325i, clocked 550 miles on it on fairly mild winter weather in San Diego, CA. with no apparent dusty conditions. My initial concern was that the filter may be allowing some contaminants to get through because if you hold the filter up against the light it appears that the filter material is too sheer to be effective. I took the airbox apart and inspected the MAF sensor and the airbox surfaces. The surrounding areas were clean with no apparent contamination or blow-by. It appears that there is some sort of static charge in play as the manufacturer claims that retains contaminants in the filter material.
I've noticed an obvious power increase and a moderate gas consumption improvement with this filter. This may have been the result of a badly restricted stock filter which had not been changed as scheduled on the warranted dealer maintenance program.
Overall I'm satisfied with the performance but will continue to monitor the filter as the weather changes and road dust becomes more of an issue in the drier months.
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By r.d. on February 25, 2013
Verified Purchase
Tired of buying filters from China for my '05 BMW 325i, I thought I'd shell out some cash for a filter made right here in the U.S.A. I'm glad I did. Despite the higher sticker price, K&N is well worth it, and if you buy it from Amazon instead of an auto parts store, it's a no-brainer. Since installing my new filter, I've noticed that my engine runs smoother, the pace of acceleration has quickend, and my engine seems to have an easier time idling. K&N advertises that its products will increase HP, but I can't really tell the difference. I also like the fact that I can clean and reuse this filter and that it can go 50,000 miles between cleanings. This means that that over time, this filter will pay for itself because I won't have to plunk down $15 to $20 every 15,000 miles (abotu a year's worth of driving for me). In all, I'm glad I made this purchase and plan to buy another K&N filter for our other car.
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Verified Purchase
Late, but not too late. K&N filters are all they're cracked up to be. Buy once and just clean every 50,000 miles, depending on conditions. Not so much to ask. And the power?? Super. Don't know about mpg yet, but assume it will improve. Our 2005 BMW 325ci performs so much better now. Have a K&N oil filter all ready for the next service. Best price by far here on Amazon.
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Verified Purchase
K&N makes great filters (air and oil). They preform better than OE buy allowing more airflow while still providing protection. The fact that they can be cleaned and reused means they will cost less in the long run. I've been using K&N air filters since 1995 and will continue to do so. I recommend replacing your OE air filter before it reaches end of life and keep it available. This way you can still use your car while you're waiting for your K&N air filter to dry after cleaning it. CAUTION! Follow the cleaning instruction precisely.
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Verified Purchase
Known as the poor-man's super charger K&N has been delivering quality filters for decades. If you have the money you might consider a K&N cold air intake system. For the price, the reliability, the warranty and the performance gains there is no better option than a filter upgrade. Avoid cheap knock offs that don't offer the same warranty or quality. Air filter choice is highly debated among enthusiasts, but you can't wrong with one of these.
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Verified Purchase
If you want better performance and fuel mileage and a purple air filter that only needs cleaned once a year and comes with a 1,000,000 mile warranty, then here you go. I put K&N filters in everything I own. I have never been disappointed! A++++
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Verified Purchase
I like K&N air filters, I have them on 4 other cars. I am a little disappointed with the fit. The filter for my M3 seems a little small. If I had simply placed the filter in the air box, there would have been about a 1/8" gap between the edge of the air box and the filter. It was easy to fix by being very careful to have the filter centered in the air box before replacing the cover. This is the first time that a K&N filter did not fit as perfectly as expected. I have driven about 300 miles with the filter and I seem to be getting a little better mpg (almost 1 mpg). I checked to be sure that there was no 'gap', and fortunately there is none. I have even gone so far as to use a camera from the intake side to be sure that I could not see a gap. So far, so good. C'mon K&N, you're better than this.
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Verified Purchase
I used a few paper filters on my E46, 330CI and was tired of throwing them away. I bought the K&N drop in filter and was pleasantly surprised to notice a mild uptick in performance. Worth the extra cash - a professional, solid product.
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