Brought my car in for service today only to discover that a critter has been nesting under the hood. A large pile of the firewall insulator was on top of the battery. The dealer said I was lucky it didn't catch fire. Is this covered under warranty? Is it dangerous to not replace? How can I replace?

 

The insulation is the least of your worries....GET RID OF THE CRITTERS! If you don't you could lose your car to fire! I'm speaking from experience.... my '97 Camry was totaled by a fire caused by critters chewing on wiring under the hood and causing an electrical short... if you DO get rid of the critters, please let me know what you did, I have yet to find a way! Now I'm trying bobcat urine crystals, the 5th thing I've tried so far!

 

Doubt the damage would be covered under warranty.

You might consider sealing around the insulation blanket to keep critters from getting under it.