2018 F150 Ecoboost
Sometimes when I use the remote I get 3 green flashes followed by 3 red flashes. The truck does start. What does this code mean?

 

just means the remote never received the conformation signal back from the truck. the truck sends a signal back to the fob confirming the start

 

Blinking green signals that a start is in progress.
Blinking red means the start was not successful.

You are getting the second message in error if the truck starts.

Mine has never worked the way I think it should. The LED is supposed to go solid green once the start is successful. I never get both, only one or the others, and in both cases the truck has started successfully.

Same when it doesn't start, I get either blinking red, or solid red, the latter which is supposed to mean I've successfully shut down the truck via the remote. When it refuses to start due to a code being present, I will get either blinking or solid. Same when I stop the truck via remote. It's as if it's just picking one randomly.

I'd have to draw the line at getting both, though. I start the truck where I can't see it at work.

 

Did you find that list of LFCs in the owner's manual? Could the OP find it in his copy?

 

I went off memory, but since you asked, I dug into my manual, yes, it is there.