'System too lean' both banks (P171 & P174) no other codes.

Anyone had similar condition or knowledge about a cause. I am looking for advice- seems to be alot of good info on this website - I don't have a mechanic I trust yet and would like to know some possible causes before I take it to anyone . The SES light has come on a few times over the past few months – seems to go out and stay out after gas fill-up – however gas mileage has definitely decreased recently.

 

i dunno what those codes are but id probably post it in advanced tech.......

 

I had the same problem. Basically, as you stated, you car is running lean, could be a number of things. 1st I would look for a vacuum leak. Other things to look at are the o2 sensors and have you changed the fuel filter latley? My car, turned out the fuel pump was going out. Do you have access to A-tap, to see how lean it is?