Check Engine Light...Going on 5 years & 20,000 miles...

T-Rex wrote:
When I bought this 2007 RV in 2015, it was 8 years old, but had only 9,000 miles on it. With so few miles at the time, my guess is that the prior owner never cleaned the K&N filter, and therefore, over-oiling of the filter isn't causing MAF sensor problems.

This is the big problem with K&N filter ! The say they last 10 years. That is for the filter itself.

They should be cleaned and re-oiled about every 5,000-10,000 miles or once a year. More often in dusty conditions.