Why's my 2019 GMC Sierra remote start not working?

There's a fair number of reasons You might not have a successful remote start with Your 2019 GMC Sierra. Let's run through some of them. Are You starting it correctly You've hit the lock button once, and then held down the remote start button for at least 2 seconds, waiting until You see the turn signal lamps flash, right If that's not it... Are You sure the car is in Park, and not neutral Also, if You've hit the remote started more than once quickly, it'll not work until You've manually inserted the key in the ignition and turned it on and off, after which the FOB should work again. Something non-intuitive is that if the coolant temperature is too hot, the remote start is disabled; this'll obviously sort itself out when the vehicle cools down. Another non-intuitive reason is that You've got the hood open; simply close it and try again. Another thing to verify is that the FOB isn't in the vehicle; if the computer detects it at that proximity, it won't start. And finally, if it's none of the above trivial things, it's likely the battery in Your key FOB is dead, and needs to be replaced.