Whining noise from engine even after turning it off

[wendy]

My 2021 Ltd HD10 is making a whining noise which makes me wonder if it's my engine fan trying to work.  Today, the whine continued for several minutes after I turned off the engine, and thinking back on my ride, I don't remember hearing the usually-frequent fan running during my last 5 miles.  What could be causing this?  And if it is fan related, what should I look for and how do I fix it?
 

 

[Andystoy19]

The next time you hear the noise stop and loosen the fuel filler cap if the noise stops it is the pressure relief valve. A few threads on hear about where it is and how to fix it if you want to or take it to the dealer if its still on warranty. 

Other than the noise it is working correctly but sounds like a balloon when you pinch the neck and let the air out.

 

[wendy]

Thank you, Andystoy19!  I'll try that.  This isn't quite as high pitched as I imagine a balloon squeaking out air, but I sure hope this is in fact the problem as opposed to the fan not working properly.  I'll update with what I find out.  Thanks again.
 

 

[DJLA]

When you turn the key off there can be a whining sound from the cpu while it is shutting down. When you check it again, stay in it and watch the gauge, if the sound stops when the gauge powers down this is the case and is normal. 

 

[wendy]

Thanks, DJLA.  This is a louder noise than the CPU, it lasted 5-7 minutes after I shut her down the other day, and it was coming from the rear of the engine.  It was a hot day and instead of the fan continuing after shut-down for its typical 30 seconds or so, there was no fan, just this whine.

After reading Andy's post, I felt confident to drive it yesterday and was relieved to hear the engine fan running when I idled for a moment (it was a cool day, so it didn't come on while I was moving).  The whine never occurred, which seems consistent with what I've now read in here about pressure relief valves and hot weather.

So now I'm hoping my fan has nothing to do with this, and will see what happens in a couple days when they're predicting hot weather again.  If it whines, I'll remove my gas cap for the final test and will post here with the results along with the question of whether I need to replace the valve.

Thanks again for your input, you guys!