I found nothing searching, so here goes. Any ideas would be appreciated!
Sometime last summer, I ran over a stray rubber base from one of those orange/white striped traffic control "cones". The ones that are kinda like a plastic sign w/ the stripes that sit on a black rubber base, but will fold over if you hit them. I ran over it with the passenger side rear wheel and shortly after (seconds, not minutes), my fuel gauge was reading empty.
Since then, the fuel gauge has been intermittently in accurate by a quarter tank or more- always reading lower than the actual fuel level. The trip odometer has become my friend.
A couple of weeks ago, when driving the temperature was showing 38 and dropped to about 23 over the course of the ride and the fuel gauge dropped to empty. The actual outside temp was close to 80. Eventually it returned to about 50 indicated. Over the days the followed, that too became intermittent and it's now largely accurate, but sometimes not.
The fuel level is always incorrect now when I fill up it often shows half when it's full or sometimes close to full, but quickly drops to 3/4 or half. It's more annoying than anything else, but I don't want to pay $$$ to have the dealer diagnose. Any ideas?
Probably unrelated, but sometimes now when I get in the car after it being parked a while the dome light doesn't come on and the fuel pump doesn't spin up.
It's crazy electrical stuff like this that drives me nuts on VWs!
Once you lick the lollipop of mediocrity, you'll suck forever.
Observations and speculations -
Due to the driveshaft, we essentially have two gas tanks, left and right. I presume there are level senders associated with each, and I also assume there is some sort of equalization pump to send fuel from one side to the other.
I have seen my gas gauge do a sudden 'half' when I knew it was full, and in my case, I knew it was related to a loose wiring connection on top of the driver's side fuel tank, underneath the driver's side rear seat. It was 'my bad', as I'd been messing around in there to run the Haldex switch cable. I broke the lock tab on that connector, and I have to get the wiring 'just so' to keep it engaged.
So I figure one of your wiring connections, probably associated with the passenger side fuel tank, got whacked by the debris. It has an intermittent fault, and sometimes you lose contact with "half" of your fuel.
I have no idea how (if at all) that ties in to the ambient temperature reading. I've seen some weirdness for those with car washes or other places where the sensor itself gets knocked around.
Then again, I'll believe just about any weird electrical gremlin associated with CAN-Bus.