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Automotive Dealership Hassles

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 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. In rare instances, consumers with dealership problems contact us. Among the most bizarre complaints we occasionally receive is that a vehicle’s Mass Air Flow (MAF) sensor required replacement and the dealership blamed the part failure on oil from a K&N air filter. This is an elegant theory with just two problems: 1) Oil will not come off a K&N air filter and 2) testing has shown MAF sensors will operate normally even after being fully immersed in oil.

In other words, the dealership’s claim is absolutely ridiculous. In every case brought to our attention (approximately 1 case for every 20,000 filters sold), the dealership was unable to provide ANY evidence to support their theory. So when we can recover the MAF sensor in question from the dealership, we do what they do not, we test it. Out of the 52 sensors we have tested to date, not one was shown to have failed due to contamination from K&N air filter oil. 28 sensors tested were in perfect operating condition and 24 sensors failed due to other factors.

The reason for these results is simple. Oil does not come off a K&N air filter. It is absorbed by thousands of micro fibers where it helps protect your engine. It does not occasionally fly off the filter, navigate turns in the airflow ducting and seek out a MAF sensor to destroy. While it is true that our cotton air filters are treated with oil, this treatment consists of a small amount of oil that is absorbed over a large area of cotton. Most of our replacement air filters contain less than 1.5 fluid ounces of oil absorbed evenly over 5 square feet of cotton. Tests have confirmed that no oil will come off our air filter even at extremely high airflow rates (greater than 1,000 CFM). As your own personal experience will confirm, when oil gets on a cotton shirt, it does not easily come off without requiring hot water and heavy detergents. It is our sincere belief that if you hold an oil-stained shirt out your car window while doing 70mph, the outside air flow will not remove the oil stains from the shirt! Neither will airflow remove oil from our cotton filter.

Even though the number of dealership problems we encounter annually (150) is very small compared to the filters we sell (2,500,000), we treat each instance as if it were our own personal problem. That’s why we always seek to solve the problem one way or another by interacting directly with the dealership on your behalf. If you encounter a hassle at a dealership, your best bet is to contact us immediately and let us deal with the dealership. Another approach is to simply go to a different dealership who will not hassle you. In fact, many dealerships actually sell and service K&N air filters.

In order to help locate a hassle free dealership, we maintain a list of dealerships that either directly sell K&N products or have informed us they will not deny warranty coverage solely based on the existence of a K&N product. Also, we maintain a list of dealerships that have been reported to us as illegally denying warranties or blaming engine/component failures on K&N products without proof as required by the law. Feel free to search our database for the dealerships in your area that you can count on after you have purchased a K&N product.

Please keep in mind that a motor vehicle dealer is, generally, not the ‘warrantor’ of your vehicle. Your dealer may be assisting you as much as possible in getting the manufacturer to cover repairs of your vehicle under warranty, but the factory may still refuse to cover the repairs. If this happens, then there may be nothing further that the dealership can do, and it should not be blamed for the actions of your vehicle’s warrantor. A dealership’s control over the approval of a warranty repair is usually limited to properly diagnosing and reporting the cause of the repair. K&N only takes issue with those dealerships who advise consumers that the mere installation of a K&N air filter on a vehicle ‘voids’ the factory warranty, or they convey to the manufacturer an unsubstantiated opinion or conclusion that a K&N air filter caused an engine or component failure, without any objective proof to support such a statement, resulting in the denial of a legitimate warranty repair.

We have found Toyota to be the easiest vehicle manufacturer to deal with and the most responsive when we point out an incident in which it appears that a dealership has inappropriately denied a warranty claim. On the other extreme, we find GM to be the least responsive with Ford running a close second.


This goes along with a few other questions in our mind like: Why do some car dealerships seek to avoid legitimate warranty claims for dubious reasons? Why do some car dealerships claim they know the cause of a MAF sensor failure when they do not even have the testing equipment that would be required to make a determination? Why do some car dealerships charge consumers more than double the price for a disposable air filter than the price charged at auto parts store? Our opinion is that a lot of companies are making a lot of money from the repeat sale of disposable air filters, including the car companies and dealerships.


K&N air filters use oil treated layers of cotton gauze because in our opinion that is how you build an air filter with high airflow and great engine protection. Nevertheless, if our oil caused a problem, we would simply eliminate it from our design. So when we occasionally hear about these claims from consumers who are told this by a dealership or “the grapevine,” we do some investigating. We’ve been flowing high volumes of air through filters on our test stands for decades and we know that oil does not come off our filter. We have become very aggressive in pursuing every instance of alleged MAF sensor failure brought to our attention (as of March 2006, we’ve had approximately 400 claims compared with over 7 Million air filters sold during the same period). We inspect MAF sensors under a microscope to see any contamination that may be present. We had a special piece of testing equipment built to electrically test for MAF sensor failure. We perform chemical analysis of alleged contaminated sensors to determine the source of the contamination. We interact directly with the dealership involved. We contact certain car companies to acquire any factual information they may have. In short, we do everything physically and professionally possible to determine what is going on. The result, throughout all this time, is we have not had even one instance of a MAF sensor failure that resulted from K&N oil. Why do certain dealerships make such allegations if they have no proof at all? You’ll have to answer that one for yourself. To view our testing results and claims history, go to our MAF sensor test results page.

Here are some of the things we uncovered:
  • We tested an over-oiled K&N air filter at a rate of 1,000 Cubic Feet per Minute on our Filtration Test Stand which utilizes an absolute filter. An absolute filter is one specified by ISO 5011 which is used to capture test dust that passes through a filter during efficiency testing. In this case, an absolute filter was used particularly to capture any filter oil leaving the filter and also to allow us to measure any amount of oil leaving the filter. We weighed the absolute filter before and after the test and confirmed our belief. Oil does not come off a K&N air filter.
  • We coated sensors with our filter oil in both controlled and uncontrolled environments, on a test bench and in vehicles, without triggering check engine lights. We created extreme conditions, beyond anything foreseeable, such as submersing a MAF sensor in filter oil and while connected to the test stand monitored the sensor readings while spraying it with test dust. Under these conditions, we were only able to alter the output of the MAF sensor. Even under these circumstances, the MAF sensor was not damaged. In addition, we were able to take this same MAF sensor, easily clean it and found that the readings were identical to the ones taken prior to the extreme testing.
  • An alarming percentage of the “failed” sensors we retrieved from dealerships had not failed at all. They tested to be functioning within normal operating parameters.
  • Few, if any, individual car dealerships have the testing equipment to determine why a mass airflow sensor has failed. Even the diagnosis of a failed sensor was not always accurate.
  • Many of the sensors tested were self-contaminated by the silicone potting compound used in the manufacture of the MAF. Some manufacturers have issued TSB’s (Technical Service Bulletins) advising dealerships of the occurrence of MAF’s contaminating themselves with their own silicone potting compound.
  • Sensors fail and are even the subject of full recalls by vehicle manufacturers. For information on recalls visit:
  • Mass airflow sensor failures are common enough among certain vehicles that certain manufacturers have a formal sensor-rebuilding program by which they retrieve failed sensors and sell rebuilt/remanufactured ones.
  • Dealerships may earn more money from a consumer for a MAF sensor replacement than they would receive from the car manufacturer for the same repair under warranty.
  • Certain sensors are now being redesigned to be more robust and less likely to fail.


Check engine lights can come on for a variety of reasons ranging from things as simple as a poorly tightened gas cap to serious engine concerns. These lights are warnings from the on-board computer that has identified something that appears abnormal with the car. It does not always mean something is seriously wrong with the car. While rare, there have been cases in which a K&N product has caused a CEL to go on because the product is allowing so much more airflow into the engine than was previously received. The extra airflow is a very good thing, but the computer warning is intended to check for leaks in the air path to the engine. Well, in these cases, it is K&N and not a leak that is causing the increase in airflow, so the light simply needs to be reset. A car could run with a K&N product for a long time with no CEL and then one day it happens. Combinations of factors that suddenly cause airflow to rise above the limit could trigger the light. An example would be a variation in normal driving conditions such as a vehicle that is under heavy acceleration, up a hill, on a cold day. All three factors would tend to increase airflow. Once again we would stress an occurrence such as this would be rare indeed and would not be indicative of an actual problem, just high airflow.  For a more detailed discussion of Check Engine Light issues, visit


Not always! In fact, it is our opinion that consumers who take their vehicle to a service provider when there is nothing seriously wrong may waste a lot of money. Consider the triggering of a CEL by a poorly tightened gas cap. A visit to a service provider with that condition could result in an expense that could have been avoided. There are many auto parts stores and service providers that offer the free service of diagnosing the reason your Check Engine Light has come on. The on-board computer produces a code which relates to a specific reason for the light being tripped.


In the unlikely event an automotive dealership or other service provider develops a belief that one of our products has caused a problem with your vehicle, rest assured that we stand behind our products and if a problem has developed that has been proven to be caused by one of our products, we will see to it the problem is taken care of and paid for by K&N. In order to ensure that we will be in a position to resolve the issue and determine the cause of the problem, it is important that you know your rights as a consumer and follow the steps outlined below.
  • Know your rights as a consumer and be persistent. More often than not, dealerships/service providers will be more prone to work with you to resolve the issue to your benefit if you persist in not being taken advantage of. If the Technician claims, for example, that the filter damaged a certain component, or caused it to fail and will not cover the repair under warranty, assuming your vehicle is still under warranty, the repair facility must be able to support their claim with evidence.
  • Have them read the warranty letter at or provide it to them and if they still are obstinate, have them contact K&N directly at 1-800-858-3333. If you can’t get them to call us, please call us yourself. You can also review relevant information at under the section “Warranty Issues.”
  • Have the service provider place in writing the nature of the problem and why they believe a K&N product was at fault. This can be written on the initial work order or subsequent documents. If they will not place their position in writing, record the name of the individual who blamed your K&N air filter.
  • Request that any parts replaced be returned to you. You need to ask this when the service writer is filling out the initial work order.
    • It is important to have the parts claimed to have been damaged available for inspection by K&N. We are able to microscopically inspect a MAF sensor and chemically test it to identify any presence of oil. By the use of specially designed equipment, we can determine if the MAF sensor is operating properly. If the parts are not available for inspection it is impossible to determine the cause of the failure.
  • Verify that the Diagnostic Codes retrieved are listed on the work order.
    • If your vehicle is 1997 or later it is OBDII (On Board Diagnostics ver.2) compliant. The Technician can plug in a scan tool and scan for the codes pertaining to your CEL as well as any pending codes that might be residing in the “Engine Control Module” (ECM). These codes will be used by your mechanic as a guideline to repair your vehicle. Each code represents a certain malady, ex. “P0101 Mass or Volume Air Flow Circuit Range/Performance problem”. As you can see, it is not an exact description of what the problem is, it simply provides a direction for the mechanic to further his/her diagnosis. The Technician can then read the “Freeze Frame” information which is a snapshot of the conditions when the code was set.


The rules and regulations adopted by the FTC, to govern the interpretation and enforcement of the Magnuson-Moss Warranty Act, are set forth in the Code of Federal Regulations, Title 16 - Commercial Practices, Chapter I - Federal Trade Commission, Subchapter G - Rules, Regulations, Statements and Interpretations Under the Magnuson-Moss Warranty Act, Part 700 - Interpretations Under the Magnuson-Moss Warranty Act. Contained within these rules and regulations is Section 700.10, which states, in relevant part (with specific language highlighted by K&N), as follows: The rules and regulations adopted by the FTC, to govern the interpretation and enforcement of the Magnuson-Moss Warranty Act, are set forth in the Code of Federal Regulations, Title 16 - Commercial Practices, Chapter I - Federal Trade Commission, Subchapter G - Rules, Regulations, Statements and Interpretations Under the Magnuson-Moss Warranty Act, Part 700 - Interpretations Under the Magnuson-Moss Warranty Act. Contained within these rules and regulations is Section 700.10, which states, in relevant part (with specific language highlighted by K&N), as follows:
“(c) No warrantor may condition the continued validity of a warranty on the use of only authorized repair service and/or authorized replacement parts for non-warranty service and maintenance. For example, provisions such as, "This warranty is void if service is performed by anyone other than an authorized 'ABC' dealer and all replacement parts must be genuine 'ABC' parts," and the like, are prohibited where the service or parts are not covered by the warranty. These provisions violate the Act in two ways. First, they violate the section 102(c) ban against tying arrangements. Second, such provisions are deceptive under section 110 of the Act, because a warrantor cannot, as a matter of law, avoid liability under a written warranty where a defect is unrelated to the use by a consumer of "unauthorized" articles or service. This does not preclude a warrantor from expressly excluding liability for defects or damage caused by such "unauthorized" articles or service; nor does it preclude the warrantor from denying liability where the warrantor can demonstrate that the defect or damage was so caused.”
Following the steps above and being aware of the Magnuson-Moss Warranty Act may not prevent you from paying an unnecessary repair but will provide you with the information necessary to seek possible reimbursement.