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In 1965, Bill Cosby came out with his third album “Why is There Air?”  Today he would be doing an album called “What is False Air?”  So how can air be true or false?  In any computer, everything needs to be accounted for or it is out of balance.  Let me give you an analogy.  When going to a movie you need to buy a ticket for admission.  Later on when a head count is done as everyone exits the movie, the number in attendance is greater than the number of tickets sold.  The difference could be known as “false attendance,” people in attendance that had not paid.  So, an engine management system works much the same way.  It is able to account for the amount of air coming into the engine (through the Mass Air Flow sensor) so that it can properly blend with the correct amount of fuel (at the injector) for the task at hand (in the combustion chamber).  As the engine exhausts that event it makes a final accounting (by the O2 or oxygen sensor) of what occurred and it finds far more air is present then was first accounted for and reports through various codes that there has been an air / fuel metering error.  False air codes, usually set a P0171 and /or P0174.  That is what we found with this KIA that had set a code P0174 – Bank 2 oxygen sensor too lean.  We traced it to a torn intake air boot (see photo).  Some other common problems that set the infamous P0171 and P0174 lean O2 sensor codes are; vacuum leaks at idle, sticking air pump sensors, dirty Mass Air Flow sensor, timing issues and weak fuel pumps but seldom is it the O2 sensor.  Remember; don’t shoot (in this case replace) the messenger (the O3 sensor).

Torn air induction boot creates false air lean code P0171

Torn air induction boot sets false air lean code P0171

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