After refueling, turn the fuel tank cap until you hear a click. Once the cap is released, it will turn slightly in the opposite direction.

Caution
When replacing the fuel tank cap
Do not use anything but a genuine toyota fuel tank cap designed for your vehicle. Doing so may cause a fire or other incident which may result in death or serious injury.
Opening the fuel tank capHorn system
Parts location
System diagram
Problem symptoms table
Hint:
Use the table below to help determine the cause of the
problem symptom. The potential causes of the symptoms are
listed in order of probability in the "suspected area" column of
the table. Check each symptom by c ...
Diagnosis system
Check dlc3
The ecm uses iso 15765-4 for communication. The
terminal arrangement of the dlc3 complies with sae
j1962 and matches the iso 15765-4 format.
If the result is not as specified, the dlc3 may have a
malfunction. Repair or replace the harness and
connector.
Hint:
Conn ...
Dtc check / clear
Check dtc
Connect the intelligent tester (with can vim) to the
dlc3.
Turn the ignition switch on and turn the intelligent
tester on.
Read the dtc by following the prompts on the
tester screen.
Hint:
Refer to the intelligent tester operator's manual for
further details.
...