po171 code means lean left bank of engine-- if cause is bad 02 sensor, shouldn't that light come on too?

Question

if parameters that set off O2 sensor light are exceeded, can that cause the po171 too lean code, but not also cause the O2 sensor light code to appear?

Answer 1

This code can be caused by a bad O2 sensor. IF the sensor is sending the wrong info to the computer it can happen. The o2 sensor won't set a code for the sensor because the ecm is happy as long as it sees an input. Doesn't matter if it's wrong or not. Other things that can set this code are intake manifold leaks and low fuel pressure.