Code GTW_w104 was reported by the “Gateway” controller in the car. The letter “w” in the middle places it among entries of the warning type.
The Gateway — the hub through which the car's controllers talk to each other, and the route software updates take. Codes from here often mean some controller has gone quiet on the bus; the real fault is usually in that controller, not the gateway.
The car is flagging that something is not right. Driving is usually still possible, but some function may be limited.
This is how the fault is named inside the car's firmware. For codes without a description it is the most precise clue there is — the name itself says what the event is about.
The text below comes from Tesla's technical documentation. We leave it in the original English so that translation cannot shift its meaning.
EPAS3P_sysStatus was missed for 5 cycle time while the car is in drive
HW or SW failure in EPAS3P or in the communication path between Gateway
Reboot EPAS3P, Gateway first. Then replace EPAS3P if not resolved
Generic task error. The task has been stopped
VEH bus has abnormal load (>70%)
Some messages on VEH bus may be dropped
SWC is running different version than the expected
PTC is running different version than the expected
Copy it exactly, letter and number included. Photographing the screen is safest — codes often differ by a single digit, and mixing them up leads somewhere else entirely.
Some codes clear after a screen restart or after the car sits locked for a few hours. If the code does not come back, it was usually a one-off glitch.
A one-off entry and a code that appears after every drive are two different things. It helps a service centre enormously if you know exactly when it shows up.
With airbags, brakes, steering and high voltage there is no point waiting it out. With the other groups you can watch and see whether the code returns at all.
Error codes are only part of the picture. For cars on TesList you also see battery health pulled straight from the vehicle, plus a price calculator that works out from current listings what a given car is actually worth today.