K&N Engineering, Inc.

K&N was founded by Ken Johnson and Norm McDonald in 1969. The name K&N came from the first letters in the founders' first names. Ken Johnson and Norm McDonald sold motorcycles and motorcycle parts and supported a K&N factory race team. Air filters soon became the primary focus of the company. In 1992, K&N introduced bolt-on cold air intake kits. K&N also released a line of oil filters with a stamped hex to accept a standard wrench off filter removal. In 2019, K&N released a line of washable home A/C filters, and began offering motor oil and wiper blades in 2021.

K&N's claims for their air filters have been the subject of some controversy, with some 3rd-party tests finding that K&N's oiled cotton gauze filters are less efficient and let more dirt into the engine than original-equipment paper filters, and that they become increasingly restrictive as they are coated with particulates. However, air filters in general become more airflow-restrictive as they collect contaminants, but efficiency typically increases for the majority of a filter’s service life. Other 3rd-party testing noted that a K&N oiled filter increased horsepower over its OEM counterpart.

Potential issues have been reported with oiled air filters on modern engines that use MAF sensors, which may stop working correctly when fouled by oil from an oiled-gauze air filter. However, there are several other common causes of damaged MAF sensors, including brake cleaner contamination, extremely dirty/contaminated filters, and loose battery terminals resulting in voltage spikes. K&N has published test results asserting that its oiled filters do not cause MAF sensor failures.