I was told that System too lean Bank 1 and System too lean Bank 2. on 2001 Ford Explorer

Codes Bank 1 po 171 Bank 2 Po 174 The "check engine" light came on so we had a 100,00 maintenance done on it. It ran for only 20 miles when the "check engine" light came on again. The shop gave us the codes but said that it was beyond their knowledge to be able to fix.

by in Carson City, NV on July 31, 2013
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1 answer 2 comments
ANSWER by , August 01, 2013
From the Haynes manual: If both cylinder banks on a V engine are lean, the fuel pressure might be too low, there may be a vacuum leak, the ECT sensor could be skewed toward a higher temperature, or the MAF signal voltage could be skewed toward a lower voltage.
COMMENT by , August 02, 2013
Thanks for the feedback.
COMMENT by , August 02, 2013
You are very welcome! A lean condition could mean the O2 sensors are picking up unburned oxygen from a cracked, or loose air inlet tube from the air box to the throttle body that the PCM does not know about as it would enter after the mass air flow sensor. Also try cleaning the MAF sensor with MAF sensor cleaner from the auto parts store.