I brought my Maxima to the dealer a few weeks ago to fix a low power and
misfiring problem.  They replaced the mass airflow sensor which seems to
have fixed the problem.  They said they had to reprogram the car's computer
with software compatible with the new sensor.  The next day I got a P0138 O2
sensor circuit high voltage (bank 1 sensor 2) code.  I continue to get the
same code about once a week since.  The dealer says I have a sensor problem.
I tell them they loaded software incompatible with the O2 sensing system
since all was fine before the SW change.  Can anyone shed some light on this
situation?