Hello dusti107,
Thank you for using Apple Support Communities.
I understand from your post that Hey Siri is no longer functioning when you plug your iPhone into your car power source. I know how important it is for you to be able to use Hey Siri while you are driving. I recommend using the following steps to help resolve this issue:
Use Siri on your iPhone, iPad, or iPod touch
Before you try these steps, make sure that your device works with Siri. After each step, see if Siri is working.
- Make sure that your iOS device has an Internet connection through Wi-Fi or cellular data.
- On your iOS device, make sure that Siri is turned on under Settings > General > Siri.
- Restart your iPhone, iPad, or iPod touch.
- On your iOS device, go to Settings > General > Siri and turn off Siri. Then turn it on again.
- If you're using an iOS device, try to use Siri with a headset. If Siri only works when you're using a headset, get help with the microphones on your device.
Best Regards