check engine light on 2004 Ford F-150 Heritage

evertime its cold outside my check engine light comes on and the scanner reads system too lean bank 2 ,evap system not ready not vacuum leaks in the engine changed gas cap

by in Killeen, TX on April 04, 2011
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1 answer 4 comments
ANSWER by , April 05, 2011
If it's bank two only - you could actually have a faulty oxygen sensor - pre cat. I would recommend monitoring fuel trims to see if the oxygen sensor on bank 2 is operating differently than bank 1.
COMMENT by , April 06, 2011
all the O2 sensor are working right and at first it said bank 1 sensor 1 engine runing lean i had replaced that one but they are all good know can it be the IAT Sensor
COMMENT by , April 06, 2011
I can't draw any correlation from a lean code to an IAT sensor failure. Bank one sensor one would be P0171. But you stated your concern is bank 2 (P0174). When you get lean codes, you monitor fuel trims and see how the sensors switch.
COMMENT by , April 13, 2011
the code came back on and my fuel trims read st1-13.2 / st2-13.2 Lt1-17.1 / Lt2-26.5 when it was 59F out side and it come and the code now is P0174 do you think it can be the Dpfe sensor or the fuel pressure regulator
COMMENT by , April 13, 2011
Lean bank 2 (P0174) cannot be caused by a DPFE sensor or a fuel pressure regulator. Again, with one bank lean code only, I would lean towards checking the wiring at the bank 2 pre cat oxygen sensor. When I suggested monitoring fuel trims, I was suggesting check to see if the sensors both switch evenly. You can do a graph read out that will look like a wavelength. I'm betting bank 2 pre cat oxygen sensor is more flat lined.