I know I have an exhaust leak on at least the passenger side header, possibly the driver side as well. About a week ago the s.e.s light came on and gave a P0171 code System too lean (bank 1). I know that bank 1 is the passenger side, and that a lean mixture can come form just about anything from a faulty fuel system to a badO2or MAF sensor. Is it possible that the leaky header has progressed so far that it may have tripped this code? I'm only reading a lean mixture for the one side.

 

yes a exhaust leak before the 02 can cause a lean code

the 02 compares the amount of air in the exhaust to the amout of air on the outside in a perfect world all the air in the exhaust should be burnt with fuel to produce max fuel efficiency/power but if you have a exhaust leak that is letting more air into the exhaust and the 02 is reading that air and thinks the motor needs more fuel to help burn that air and after so long the computer realizes their is a problem because it keeps giving fuel and its still lean so it throws a code mine hasnt done it yet but im sure its soon to come

and if im not mistaken bank one is the drivers side of the car i know some manufacturers swap sides and **** but ford i think does b1 right side facing front of motor b2 left side facing front of motor

 

Thanks, hopefully replacing the header gasket will do the trick. I'd hate to think Ive got a MAF thats gone bad. From what Ive read they aren't exactly cheap.

 

it may not be the gasket it could actualy be the header its self leaking the passanger sides are known to do that

 

If its the header is that something that will need to be totally replaced or is able to be repaired?

 

It could be re-welded but if you're going through the trouble of taking it off you might as well put soemthing better on.

 

re weld if you are short on cash

mac lt headers if you have some cash to spend