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Questions and Answers

Ford Ranger DTCs P0171 & P0174

Q. Hi Vincent, My 2001 Ford Ranger, 3.0 liter, automatic transmission with 55,000 has a Check Engine Light on, and my new Autoxray EZ-Scan 6000 Vehicle Scanner reports trouble codes P0171 & P0174 "System too lean bank 1 & bank 2".

Ford Ranger DTCs P0171 & P0174

The code book gives many probable causes so I'm not sure where to start. The Vehicle Scan Report also shows that some of the Readiness Test did not get completed during the "trip" and "drive" cycle recommended by the Autodata Diagnostic Trouble Code book. Questions:

  1. Can you give me some pointers on where to start?
  2. Before I got the EZ-Scan 6000, I disconnected the battery without using a "Computer Memory Saver" device to clear the error codes. Does this mean that the drivability settings and codes have been erased and the vehicle will no longer be able to go into the "Limp Home" mode?

Thank you in advance for your time.

A. 1. Here is the best place to start:

Ford F150 Codes P0171 & P0174

Ford Expedition P0171 & P0174

Ford Mass Air Flow Sensors

2. Disconnecting the battery will erase the stored codes and learned values. It will not effect the "Limp-in" mode of the PCM. Simply drive it for 10 to 15 miles to allow the PCM to relearn the values.

Additional Information provided courtesy of AllDATA

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