Need Help With Trouble Codes PO171 and PO174 - Ford Mustang Forum

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post #1 of 2 (permalink) Old 05-30-2009 Thread Starter
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Need Help With Trouble Codes PO171 and PO174

My '98 Mustang GT has been lighting up its Check Engine light when going above 3000 feet or so. I live at 200 ft, so when the codes are erased the light stays off until I do a little climbing. The codes are Diagnostic Trouble Codes (DTC's) PO171 and PO174 using my Actron PocketScan Plus CP9410. The Actron instruction manual says these codes are "Bank 1 System too lean" for PO171 and "Bank 2 system too lean" for PO174. My confusion is that my Haynes Manual for Mustangs '94 thru '98 say those codes are "Heated Oxygen Sensor unable to switch, right side" for PO171 and "Heated Oxygen Sensor switching slow, right side" for PO174.
So the Haynes manual says that both codes are on the right side, and the Actron Instructions says one is Bank 1 and one is Bank 2 which means opposite sides.
So can anyone out there help me proceed with trouble shooting this predicament, and how to repair this problem? Do I replace both right sensors or one on each side, and which ones since there are 2 on each side? Thanks for your help in advance!

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post #2 of 2 (permalink) Old 05-30-2009
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Here is an explanation of the codes and what may be causing it. OBD-II Trouble Code: P0171 System Too Lean (Bank 1)

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