i have a 00 durango and i am getting 4 miles to a gallon. i keep throwing p0171 which is making me run rich. so i first changed the o2 sensor that didnt work so i put new plugs in and the code still comes up. my buddy at work said that on the 4.7 that they are known to blow the intake manifold gasket so i just did that today and drove 15 miles and the code pop up again. does any one know what else could be wrong or if you had this problem please let me know what i can do to fix it. thanks

 

P0171 System too Lean (Bank 1)

This is the 02 sensor BEFORE the cat. I think there are 2 before and 1 after on that year. Make sure there is no power steering fluid leaking into the plug.

 

I doubt your getting 4mpg, maybe 10ish or so. I know what 4mpg is like xD... As hydra mentioned check the precat o2

 

i just looked on the truck there is one in front one in back. do you think a new ecu would fix this problem

 

i get 140 miles to a tank of gas i have a 25 gallon tank. i would love to see 10 mpg that is way better then what i am getting

 

140/25 is closer to 6 gallons (5.6 MPG)... Unless you are running your Durango till it runs out of gas... I'd say you are getting better mileage... You divide mileage by total gallons filled up... Not by the total tank capacity...

 

Joey we have seen this problem from a power steering fluid leak (thanks master tech). What happens is the power steerring fluid leaks onto the o2 sensor wires and after a while it causes the wires to arc at the sensor which basically bypasses the sensor altogether giving the pcm a false reading and causes this problem. Get under the D and unplug the sensor and check out those wires.