When you try to turn on the climate controls from your Tesla app to pre-heat or cool your Tesla, you might get a failure message "Climate On failed. Climate failed to start." This means something is preventing the Tesla app from connecting to your vehicle to activate or deactivate the climate controls. You can follow the troubleshooting steps to fix the issue. If none of the steps works, the problem could be hardware related, and you'll need to book a service appointment.