The battery in your FOB will last about 4 years or so. If it'* acting up, then change your battery. The battery you will need is CR2032.
Different years might be a little different, but the task should still be the same. You can use a quarter to open your FOB. If a coin does not fit then you will need to use a small screw driver.
Give the quarter a twist and the FOB will pop right open.
Remove the rear cover and you will find the battery.
The circuit board will pop right out.
The battery then slides right out.
Then slide in a new battery.
Put the rear cover back in place and snap it closed.