Quote Originally Posted by 7milesout View Post
Other possible causes are: 1st gear changed its ratio, and now it's wrong.
Someone opened up your transmission and changed the ratio of 1st gear, and now it's wrong.
1st gear has decided that it wants to identify as a different gear, and now it doesn't like being dead-geared.
You drove the vehicle, and doing so has lead to this problem (hint: Never drive it, or problems).
It has always been the wrong ratio, it's just now getting around to letting you know.
I'm sure there are other legitimate possibilities as well.