Rattling

Hello, it could possibly be something as simple as a loose exhaust heat shield. It could be as complex as an internal mechanical component. Sadly, it's hard to say until someone with a trained ear can hear your noise and recommend a diagnostic path, or give you first hand advice.

If it's metallic rattle then it may be a metal heat shield for the exhaust. Only a hands-on inspection will determine the cause for sure. You can get under there when the engine is cold and look around for a shield that is loose or you could use this link to find a good shop near you. https://repairpal.com/repair-shops Alex