P0171 Lean fault fix problem solved

[snowshoe]

When climbing mountains, my 2000 echo with 60k miles on it, would have the check engine light come on and stay on. Took it to autozone and the code was p0171 lean fault. I took out the MAF(a plug and 2 screws) (located on the air intake plastic assembley just left of the front of the battery, looking at it facing the car). Shure enough the little thermistor (looks like a amber droplet of plastic about the size of a kitchen match head with 2 wires on it) was encrusted with black dirty muck. Cleaned it with a soft artists brush and alcohol(electronic parts cleaner). Everything ok now.
Just in case this happens to you this may be of help.

[snowshoe]

Ps: I did clean the 2 little air flow sensor resistors also(with sensor upside down looking ito it with a light you can see them). Soaked them in alcohol(filled it up and let it stand for 5 min) then flushed it out with computer key board cleaner.