Code TAS2_a201 was reported by the “Air suspension — newer control board” controller in the car. The letter “a” in the middle places it among entries of the alert type.
The newer air suspension control board. The codes mean the same as the TAS group, and the descriptions tend to be more detailed — including how often each check runs.
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.
This alert is a load-shed request from Gateway (GTW) due to the voltage of the LV bus.
Set: This alert is set when the GTW sends the CH_hvBatteryLow signal, which is a carry-over signal from Electronic Air Suspension (EAS). Despite the name of the alert, this message indicates to the air suspension controller that the LV system (not necessarily the LV battery or HV battery) is at a low voltage, and so it sends the controller into a limp mode to reduce the electrical loading on the LV system. It is likely to see this during a load-shed event where the LV system is not being properly supported by the DCDC.
Clear: Clearing of the low high-voltage battery signal (CH_hvBatteryLow).
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.