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 capInstallation
Notice:
Do not heat the vehicle body, emblem and name plate
excessively.
Hint:
When installing the emblem and name plate, heat the vehicle
body, emblem and name plate using a heat light.
Standard heating temperature
Install no. 4 Back door name plate (for 4wd)
Clean the vehicle body ...
Brake
General maintenance
Inspect brake lines and hoses
Hint:
Work in a well-lighted area. Turn the front wheels fully to
the right or left before beginning the inspection.
Using a mirror, check the entire circumference and
length of the brake lines and hoses for:
Damage
Wear
...
Occupant classification sensor power supply circuit malfunction
Description
The occupant classification sensor power supply circuit consists of the
occupant classification ecu and
the occupant classification sensors.
Dtc b1793 is recorded when a malfunction is detected in the occupant
classification sensor power
supply circuit.
Wiring diagram
...