How to fix Google Assistant Not Working
If Google Now doesn't work on your phone while driving, try restarting your phone first. If that doesn't work, follow these steps.
Make sure a third-party program, such as DriveMode, is installed. Such programs can interfere with connecting to the Internet while driving. If you have DriveMode installed, try disabling or removing it. Now, just in case, restart your phone and try Google Now again!
Voice control does not work (phone)
If Google Assistant can't recognize your voice on your phone, or if you need to say "OK Google" twice to launch Assistant, check the launcher you're using.
Third-party launchers can sometimes cause problems with the Assistant. Switch to the default Android launcher, try the Assistant, and see if it works. If so, contact the developer of your launcher for details.