"The K&N filter might have something to do with your issues. From what I understand, even slightly over-oiling the filter can lead to a fouled MAF sensor, which sounds like it may be one of the things contributing to your CEL codes."
"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. Nevertheless, I will be cleaning the MAF sensor in case it's gotten dirty for any reason."
The following is strictly MY opinion from years of direct experience. (with K & N air filters)
Whenever I see a K & N air filter, I do the following:
1. Remove the K & N air filter and all related components.
2. Hold the filter above the appropriate sized waste receptacle.
3. Open your hand.
4. If the filter falls into the waste receptacle, go to step 6.
5. If the filter fails to fall into the waste receptacle, repeat steps 2 and 3 until it does, then go to step 6.
6. Replace the K & N filter with a new OEM pleated paper element.
If the OEM airbox and other intake components have previously been removed/modified, you will need to replace them. Look for a vacuum leak in the intake system. When the engine is running rough (cold) spray propane (unlit from a torch) around all the vacuum hoses and connections on the engine. When the engine smooths out, you found the leak. Or, it's sufficiently warm to run smoothly. In that case you'll need to start again later, . . . . when the engine is cold.
Chum lee
