K&N Mass Air Flow Sensor Statement

Every stock replacement air filter we sell comes with this sticker, which we advise consumers to place prominently on their air box. The sticker is to alert service technicians that they should not throw away your K&N air filter because it will last for the life of your vehicle. When service technicians see this sticker it means “STOP SELLING THIS CUSTOMER DISPOSABLE AIR FILTERS OVER AND OVER.” In our opinion, this is why some dealerships or service providers may attempt to discourage a consumer from using a K&N air filter or worse blame a vehicle repair on our lifetime air filter. Most dealerships provide excellent service and fulfill car warranty obligations without issue, argument or tardiness. The rest of this discussion is about a minority of dealerships who are either misguided or misinformed.

We are aware of the “urban myth” (K&N News Story) created by a few dealerships that a vehicle's MAF sensor can be contaminated by K&N filter oil. No evidence has ever been provided to support this “myth” and years of diagnostic testing by K&N has shown that not only is this allegation not real, it is not even possible. In our opinion, it is an excuse for a dealership and/or the vehicle manufacturer to avoid a legitimate warranty repair. In the last 4 years, we have sold over 10,000,000 lifetime air filters and received only a few hundred calls from consumers who are having dealership or service provider challenges. We believe that Dealership's or service provider's real incentive may be to discourage the use of reusable products so they can sell disposable products over and over. In order to provide consumers with added comfort that they will not be placed in a bad position by an improper warranty denial, we offer our Consumer Protection Pledge.

K&N MAF Sensor Videos

Mass Air Flow Sensors
Intro & Test Results Summary


Can Oil Come Off Our Filters?
High Airflow Testing & Engine Air Filter Dynamics


What Does It Take to Foul a MAF Sensor?
Extreme Testing


What Can Contaminate a Mass Air Flow Sensor?

No dealership or service provider, when contacted, has ever been able to provide us with evidence to support this “myth,” and in fact, our investigations have revealed that even authorized dealerships are simply speculating and do not have the test equipment necessary to know whether the sensor has failed or why. In the last 7 years, we have had more than 300 actual sensors sent to us by consumers with documents showing dealerships claimed our product had caused them to fail. Microscopic, electronic and chemical testing revealed that none of these sensors were contaminated by K&N oil (K&N Detailed MAF Sensor Test Results). What is perhaps the single biggest clue to what is going on is that over 50% of these sensors sent to us were not broken in the first place for any reason. Click here for more information on how this may happen.

The oil treatment on our cotton is very small (usually less than 2 ounces) and is a critical component of our filtration technology. There is nothing unusual about the use of oil as a tacking agent to improve air filter efficiency. In fact, certain Ford Motorcraft and Fram disposable air filters are treated with oil. This makes us wonder if it is only the oil treatment from reusable lifetime air filters that is alleged cause a vehicle problem?  The idea that oil comes off our filter throughout its life is truly ridiculous. Just like oil treated disposable air filters, once our oil is properly and evenly absorbed through the cotton, no oil will come off, even under extreme engine conditions. We have even conducted a test with an over oiled K&N air filter in which we flowed 1,000 cubic feet of air per minute for over twelve hours (few cars or truck could generate even 500 cubic feet of air flow). The use of an absolute filter confirmed that no oil came off the K&N filter tested, even in these harsh conditions.

We have tested many MAF sensors claimed to be damaged. We can fully diagnose their condition and likely cause of failure. For a full discussion of our MAF sensor test protocol and findings, see K&N Mass Air Flow Testing Results and Findings.

Not one of these suspected MAF sensors sent in for laboratory evaluation was shown to have failed due to contamination from K&N filter oil.

We are the solution
We are so confident about our testing and the quality of our product that we offer a Consumer Protection Pledge. So if you ever get in a bind with a dealership, call us because we are the solution.

Other Information:
An In-Depth Look at How Mass Air Flow Sensors Work