Fuel Gauge - Incorrect Level Reading

[soulreapersteve]

Posting this thread up so it can be indexed by Google (hopefully). There were a handful of threads about the gauge not reading correctly a couple years back, with MY 13/14's, but none of those fixes helped in my case. This seemed like a one-off issue but just in case this happens to someone else, especially a car newbie such as my self...

2015 FRS for reference.
(tl;dr at the bottom)

Anyhoo, about 2 weeks or so back, I went to fill up as I usually do. After starting the car, I noticed the gauge only moved to about 3/4 full. I thought the pump shut off prematurely, so I drove around for about 10 miles and went to go fill up again at a different gas station. Pump shut off couple seconds later and thought that was odd. Gauge was still reading 3/4 full. Also noticed a few days later if I let the car sit idle for about 3 to 4 minutes, the gauge would fluctuate between half and 3/4.

Hopped on the forum and found old threads mentioning very similar issue that I was experiencing. They fixed it by disconnecting the battery, driving until there was half a tank of gas remaining, and/or driving until very little fuel remaining. None of those methods fixed it in my case.

Thinking back to when I was observing my buddy replacing his Audi's fuel pump, he was telling me how the whole system worked. That got me thinking it was either the float in the tank or the gauge it self was the issue. So I took the car in under warranty. Few hours later, they called me back and said the "fuel sender unit was broken" (guess they kept it non-technical after reading the paperwork) and replaced it with a new part.

tl;dr > Fuel gauge was giving incorrect level reading, tried a couple of fixes from old threads, didn't work, thought it was the float or gauge, tech said it was the fuel sender unit, replaced and now working correctly.

Full details of their work notes are below. Hopefully, this helps someone in the far future if it were to occur.