Code UI_a046 was reported by the “User interface” controller in the car. The letter “a” in the middle places it among entries of the alert type.
The application layer of the touchscreen. Most codes from here are everyday notices the car shows the driver — an open frunk, a door left ajar, a status message about some feature. They are not hardware faults.
The most common type. The car logged the event and may have shown it on the screen. The range is wide — from something trivial that clears itself to something that needs attention.
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.
Backup camera reported an error when streaming. There is a high probability of a HW fault or disconnected harness.
Backup camera reported an error when streaming.
Autopilot trial period has expired
Autopilot trial was active and has now expired
Autopilot trial has expired. Autopilot no longer available
Tire pressure sensors unable to measure tire pressure. Triggers tell tale light on the cluster
TPMS resumes standard operation
Unable to measure and report tire pressure
Shift stalk request but driveRail is not ON and brake pedal is not pressed
Press brake to turn driveRail ON and shift
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.