1997 Ford Thunderbird Trouble code issues

1997 FORD THUNDERBIRD
153,000 MILES • 4.6L • V8 • AUTOMATIC
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MANDMLVRS
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Have two codes, Po171 system too lean Bank 1 and Po174 system too lean Bank 2. What is my problem?
Have recently replaced catalytic converter on drivers side as well as the o2 sensor right next to it. My dash light still says service engine soon. (I had the codes reset) Thank you, Marilyn
Dec 2, 2013 at 2:26 PM
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WRENCHTECH
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Those codes indicate the engine is running too lean. I see these codes a lot on a Ford and it is nearly always caused by a severe vacuum leak. Listen for the hissing noise at idle and try to follow it to it's source. It usually has something to do with the PCV hose and it's rubber fitting with holes sucked through them.
Dec 2, 2013 at 2:37 PM
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SATURNTECH9
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You could have a vacuum leak or a bad mass airflow sensor.I would check for a vacuum leak and go from there.
Dec 2, 2013 at 2:39 PM
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