Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.
If the P0171 is combined with the P0174 code, the problem is likely caused by an intake leak or the Intake Plenum Gasket and seals. If there are no intake leaks, the next step is to replace the air filter and clean the airflow meter. If the problem persists, the front oxygen (O2) sensor may need to be replaced.
Link to a website with information on how to replace the Intake Plenum Gasket and seals:
1999-2003 Fords Windstar Code P0171
There is Factory Service Bulletin for the following Ford Models:
2009-2010 Ford F-150
2009-2011 Ford E-150
2009-2011 Ford E-250
2009-2011 Ford E-350
2009-2011 Ford E-450
2009-2011 Ford Expedition
2011 Ford F-250
2011 Ford F-35
Ford Factory Service Bulletin OBDII Code P0171
2004 FORD F150 P0171, P0174, P0301, Misfire, and Lean Condition
The cost to diagnose the P0171 FORD code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
- Fuel injection system does not operate properly.
- The amount of mixture ratio compensation is too small. (The mixture ratio is too lean.)
With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the theoretical mixture ratio based on the mixture ratio feedback signal from the heated oxygen sensors 1. The Engine Control Module (ECM) calculates the necessary compensation to correct the offset between the actual and the theoretical ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the ECM judges the condition as the fuel injection system malfunction and light up the Malfunction Indicator Light (MIL) (2 trip detection logic).
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