Every once in a while I my check engine light comes on and it gives two codes: P0171 and P0174, both of which mean "Too Lean" (Bay 1 & 2). If I clear the codes and check engine light goes off and stays off for a while, but a couple days later it might come back on and do the same thing all over again. Whatever problem this may be, it causes absolutely no noticeable symptoms other than the light coming on. Any idea what may be causing this?

I have a K&N filter in it. I took it apart and found that it appears as though the dealership tried to clean and oil it for me, as there was excess oil dripping out of it when I took it out. I wiped off the excess and sprayed off very first sensor that is upstream from the filter. There is another sensor upstream from that one that is round with a bulb-thingy in the middle of it. Kinda looks like that thing in the back of your mouth between your tonsils. Anyway, I don't know which of these is the MAF sensor but neither looked dirty and I did spray both of them off with WD40. That was the first time the CEL came on. It went off for about 2 days then came back. So I wonder if it's the same problem and i just didn't get all the dirt off, or if I'm out in left field here.

 

Don't use WD to clean anything...use either brake parts cleaner or electronics cleaner. The MAF sensor elements look somewhat like light bulb filaments. If they are dirty, the MAF cannot accurately measure the mass of the incoming air.

Here's some SEARCH help - Keyword "P0171 P0174" and "cleaning MAF"

Steve

 

I am sure is your pcv ith elbow, just go ahead and replace it.

 

Tried that before I posted, but thanks anyway.

 

Did you follow the hose till the wall?

 

What?