Gas gauge

The other day when filling the tank, the gauge did not go all the way to full 10 blocks. The tank was full as it clicked off on second nozzel lever pull.
Thought it would correct after a few minutes as it usually does, but did not. Today we drove 300 mile trip and noticed the gauge began turning off blocks as it should as gas was used. It stopped at about right number of blocks for 300 miles. Refilled tank but gauge stops at 8 blocks again.
Is this a known problem? Is there an easy fix, say disconnecting the 12V battery for several minutes which might reset the gauge computer? I have already scheduled it into toyota for a look/see.

 

Well did the recalibration routine today and the numbers did what the above poster said it would. So tommorrow I will be out and about and fill the tank (on level ground!) and see if the gauge goes full 10 blocks.

 

That did it! Wife said she filled the tank, nozzel clicked off and gauge steadily climbed from 3 bars to 10.
Thanks cwerdna. Now I can cancel the Toyota appointment and save $60 service charge. And if they should ask, I will tell them I found the answer here, then hold the phone from my ear as !@#$%^&*() spews forth!