I have an 08 Silverado 1500 with a 5.3L. I put a K&N cold air intake on it and about an hour after driving it the check engine light came on. I am now getting a code that says "system too lean bank 1,2,3 and 4". I put the factory intake back on thinking it would fix it, but the light came back on... Does anyone know what is causing this?

 

You made sure to hook up the MAP sensor didn't you? Not sure what else would cause something like that, I have the K&N cold air intake on mine. I unhooked it once while it was running to check something on the throttle body and it killed the truck and I also got a light. I just unhooked the battery, then hooked the battery back up and everything went away.

 

Could be a couple of things. Oil sucked off the K&N and is now coating the MAF sensor. Fix is use less oil and get some MAF cleaner and clean it a couple of times. I don't know about the 08 models but i know with my 04 6.0 I got myself a tune to have the MAF sensor read the more air it was pushing thru. I also run a K&N. Hope this helps