2012 LSV Cylinder #5 fuel injector open

[audiofn]

Hey all my boat is going to drive me to drinking this year I swear.  We have a 2012 LSV with a 409 Indmar motor.  After 2 weekends were it looked like I finally had everything squared away, I was out with family and friends and the motor started to run real bad again.  When I looked at my onboard diagnostics I got the SPN 3266 (FM1:5 02 2/2) code.  So I figured no big deal head back to the dock and drop a new O2 sensor in.  I had one at the house so had hoped it would be that easy. I put my reader on it at the dock and I am getting a cylinder #5 fuel injector error as well as bank 2 pre and post cat O2 sensor errors.  I only had 1 O2 sensor left so I replaced the front port side (bank 2) O2 sensor.  That sensor ohm tested as bad.  That made the pre cat error go away but still have the post cat error come up when I run the O2 test,  I am a second guessing what bank would have my number 5 injector because of the O2 happening at the same time.  I assume them going out at the same time means they are connected?  Isn't #5 cylinder on the starboard side however?  If so I would have assumed the O2 sensors on that side would have been the ones to go?  You can smell the fuel when the boat is running and even see it in the water sometimes.   Any help would be amazing as I am really getting burned out working on this boat every time we take it out.  Am I wrong to think that #5 cylinder is on the starboard side of the boat 3 up going from the stern?  See below

      Stern of boat

             Belt

1                            2

3                            4

5                            6

7                            8

    Transmission

     Bow of boat

Edited September 3, 2023 by audiofn