Code UI_a116 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.
Uncorrectable memory errors were reported by the memory controller
Number of uncorrected memory errors > 0
Memory controller is not reporting uncorrectable errors
Corrupted data was provided to the operating system when reading memory
The video pipeline emitted an error.
An error was posted on the bus created by the video pipeline.
The Ecall audio configurator 'Ecall Analog microphone' test failed
Ecall analog microphone RMS amplitude is lower then EcallAnalogMicRMSThreshold (0.06)
Ecall analog microphone test has to pass
Ecall voice issues or Ecall unavailable
Premium amplifier boost power failure
Premium amplifier boost power detected as failed during initialisation
Loss of audio premium amp boost functionality
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.