For the last couple of weeks my truck has been suffering from P0171 and P0174 which is a "Lean Condition for Banks 1 and 2". I followed just about everything I read about the codes in forums. The PCV valve is new and there are no cracks on the elbow connected to the back ot the throttle body. The MAF has also been swapped out. The truck also threw a P0172 which was caused by a leaky lower intake manifold gasket leak and fuel injectors #1 and #3 were changed because they were not functioning properly. I also had the throttle body cleaned. I disonnected the battery to clear the CEL codes and drove the car for about 66miles before the same codes, p0171 and p0174 returned. I'm starting to run out of options because I will need to smog the F150 by December '05. I'm trying to hold off in bringing the car to dealer, but the truck idles good and runs fine. The only issue is that CEL which I see all the time. Last December '04, I had a 90K done to the truck which also included the fuel filter, spark plugs, air filter, and oil. I'd appreciate any kind of input for this dilemma.

 

One other thing that comes to mind.....

Maybe you have an exhaust leak of some sort that is letting in oxygen before the sensors.....which in turn is diluting the mixture and giving a lean mix reading.