My friend has a 2003 Ranger Edge with 4.0 V6. The truck runs great, but the check engine light is on, so it won't pass inspection. I read the codes and got these two, P0171 and P0174. They indicate that both banks are lean. Does anyone know what might be causing this? Is it bad O2 sensors?

 

It's not the 02 sensors. Most likely a vacuum leak. Check out:

https://www.ford-trucks.com/forums/9...1-and-2-a.html

https://www.ford-trucks.com/forums/7...01-ranger.html

 

Thanks for the tip. I'll take a look at those threads.