I am hoping that someone here can help me understand what may be causing this to occur.

2009 G37s sedan
80k miles
original battery
no other issues known at this time

 

Holy heck that's hot. Do you know what your voltage is at when idling? Is it stable?

 

I have the same issue. I chalked it up to the light in the gauge failing. Maybe it's the alternator failing though. These cars are ridiculous that they didn't come with volt and oil pressure gauges.

 

LOL! Please ignore that temp readout. That thing is never accurate when temps are above 80. It was actually about 93 that day.

No, I don't know the voltage. And, the issue occurs when idling or driving. It's also inconsistent. Sometimes it will only affect the high-end of the tach then other times will also bleed over to the speedo.

I was thinking that it may just be the age of the battery or maybe a faulty fuse.

 

I agree...it would be nice to have a volt gauge! The worst part of this issue is that I have been considering selling the car to get an Audi Q5 but if I have to pump mega $$$ to get the dash repaired, I will probably just keep the damn thing a while longer. GRRR