I cannot hear Siri and she cannot hear me on my carplay
We're glad you thought to ask Apple Support Communities about the issue you're having with not being able to hear Siri audio, and Siri not hearing you when connected to CarPlay. Take a look at the steps in the following guide to see if they help to get Siri going again: If you need help with CarPlay
If you haven't already, be sure to reach out to your stereo manufacturer to check for available firmware updates, and possible settings that could affect Siri audio. Let us know how it goes.