WARNING: This page is about a different car, the 2013 Acura MDX, 2012 Acura MDX, 2011 Acura MDX, and 2010 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect the rear A/F sensor 6P connector (A), then remove the rear A/F sensor (B).
Fig 1: Identifying Rear A/F Sensor 6P Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Install the parts in the reverse order of removal.