This Is what the K&N page says about Mass air sensor

Will a K&N filter cause my vehicle’s mass air sensor to fail?

At this time, K&N is unaware of any evidence that K&N air filter oil from a K&N air filter can damage or cause the malfunction of a MAF sensor, regardless of the make of the vehicle involved. K&N takes seriously any claim that one of its products is incompatible with its designated application or can damage or cause the malfunction of any automotive component. Such claims are thoroughly investigated and, when appropriate, testing is undertaken to determine their merit. In the case of MAF sensors, ongoing tests have shown that contamination from K&N air filter oil has not caused any failures or malfunctions of the MAF sensors in the test vehicles. K&N is aware that MAF sensors can become contaminated for a variety of reasons, unrelated to a K&N air filter (such as backfiring, blowby, leaking airbox or leaking intake duct)