Low Voltage Fault Verado 300 2012

New to forum and hoping I can get some help - here in NH all shops are eyeball deep in winterizing so I am forced into DIY mode. Just trying to catch ONE more bluefin this season! 2012 twin Verado. 1300 hrs. Recently started getting Sensor Fault Check Engine after running approx 10 min. Guardian then reduces rpm to 4200. Diacom scan indicated low voltage. Followed suggestion to check/clean all terminals and also replaced trim sensor. On test run today I watched the Smartcraft gauge entire time. 14.2 v when Fault tripped. Also weird was that on test today, after Fault, I ran Diacom on engine. No record of today's fault (same 10 as prior scan). Many thanks in advance for any guidance here. Bob Weathersby Seacoast NH Sportfishing

Low voltage can be on the 5v reference.....