I have an auto nissan 2002 se. a few months ago I had ses light on Nissan said rear o2 sensors need replacing. Since then light has gone out but car appears to get bad mileage regardless of the mpg readout 22-24 mpg.
has anyone experienced this.

what is engine rpm suppose to be at idle ?

1st is there a tsb for 02 sensors ?

2nd Are they easy to replace ?


thanks in advance