I have a Subaru Impreza WRX wagon with 110K miles on and, naturally, it has developed a few rattles. One that's particularly annoying is coming from the dash near the windshield to the left of the wheel (very near the VIN tag). This is a "sometimes" rattle, making it hard to track down.
What is the likely cause of this rattle and how do I fix it?
I just realized that I never followed up on this question:
It turns out that the rattle was coming from the connectors holding down the large trim piece that lines the base of the windshield. It's a long piece of curved plastic with vents for the defroster and happens to have the VIN tag attached to it. If you pull this piece (using a wrapped screwdriver and some care), you'll see that it's held in place by some fiddly plastic fittings that insert into clips attached to the rest of the dash.
These little plastic bits are not held firmly in place and will rattle like a can of dried peas if you shake them. However, a dab of silicone on each one greatly reduces the rattle while not interfering with their ability to reconnect to the rest of the dash.
The vin tag can get loose sometimes. It should be up by your windshield on the left side. They are intentionally not made easy to access. Which begs to question why they would also frequently become loose on old cars but I digress. Because of how hard it is to access I would suggest using some clear RTV on each end to stop it from rattling. The added bonus is that is clear so it should not obscure the numbers if you get it in the wrong spot.
Good luck.
Check for speakers around that location. Could be a loose speaker or a damaged speaker that rattles on it own or when music is playing.
