Thanks for visiting the Apple Support Communities Busterbrown21,
According to Honda's website, not all vehicles will support text messaging via the Honda HandsFreeLink with iPhone. If it a vehicle does have text messaging support for iPhone, it may only work with certain model iPhone devices on specific iOS versions.
To confirm if your vehicle supports text messages from your iPhone, you can visit Honda's HandsFreeLink compatibility check website here: Honda HandsFreeLink.
For more information and to get more help, we recommend reaching out to Honda directly. They will have the knowledge and resources to help answer your questions, and offer troubleshooting if it should be working. You can do that here: Honda FAQ.
Best!