hey i was wondering if anyone out there can link me to a thread about the P0171 or P0174 code, or can give me any hints as to what it might be. i looked it up and it said the mixture is "too lean". my guess is that its something to do with the intake sensor... but i really dont know. I have a 2001 4.2L with about 140,000 miles on it. any help would be greatly appreciated!

 

Hi

When is the last time you cleaned your MAF ? Check the Clean your MAF thread here. Helped me, I had the same codes. When I pulled my MAF out there was visible residue on the 2 filaments. Cleaned it, and truck ran noticably different. Check your air filter also.

Vince

 

I could be wrong, but I think if both banks are lean 99% of the time it is a vacuum leak. Cleaning the MAF, correctly, can't hurt. But also check those vacuum lines.

 

Both Codes at once usually mean MAF or PCV elbow back by the firewall that plugs into the manifold.- could be either or.

You clean the MAF and replace the elbow.

 

thanks guys, I put in a new k&n filter about two months ago, so i think im all set there and the two codes mean both banks. i will check the MAF and all the vacuum hoses/elbow.

 

You can also put "174" or "171" into the search function here. You will get tons of links to look at, as this topic is probably the most talked about around here. To point you to one specific link would almost be unfair to the other 3000 of them out there.

 

lockes1. Do yourself a favor and start at the vacum line. Check the hose tha connects to the pvc. It will run to the lower intake. The check the elbow that is under the tb. Make sure you unplug the neg bat cable. It clears your codes. Goodluck Ben

 

Upper Intake The line runs into the upper intake back by the firewall.

 

I had this problem a few months ago and when thru the pvc elbow and MAF sensor checks and didn't find a thing.

Mine was the fuel filter. Try that.

 

Check the upper intake gaskets for vacuum leaks.