I keep haveing this code come up when it is colder than 10 deg , I was wondering what could be causing this because its only a winter issue

 

Most likely the IAT ( intake air temp ) sensor is at a limit. The computer likes to see a change but if it's cold enough outside it will just stay at the max/min threshold.
Must be MN or in the area. My mom's from there and we definitely avoid family visits in the winter time.

 

DTC P0171 Fuel Trim System Lean Bank 1
Circuit Description
The powertrain control module (PCM) controls a Closed Loop air/fuel metering system in order to provide the best possible combination of driveability, fuel economy, and emission control. The PCM monitors the heated oxygen sensor (HO2S) signal voltage and adjusts the fuel delivery based on the signal voltage while in Closed Loop. A change made to the fuel delivery changes the long and short term fuel trim values. The short term fuel trim values change rapidly in response to the HO2S signal voltages. These changes fine tune the engine fueling. The long term fuel trim values change in response to trends in the short term fuel trim. The long term fuel trim makes coarse adjustments to fueling in order to re-center and restore control to short term fuel trim. You can use a scan tool in order to monitor the short and long term fuel trim. The ideal fuel trim values are around 0 percent. A positive fuel trim value indicates that the PCM is adding fuel in order to compensate for a lean condition. A negative fuel trim value indicates that the PCM is reducing the amount of fuel in order to compensate for a rich condition. If the PCM detects an excessively Rich or Lean condition, the PCM sets a diagnostic trouble code (DTC). The long term fuel trim diagnostic parameter is an average of several of the long term speed load learn cells which the PCM selects based on the engine speed and the engine load.


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