Code TAS_a290 was reported by the “Air suspension” controller in the car. The letter “a” in the middle places it among entries of the alert type.
Tesla Air Suspension — the air chassis: compressor, valves, ride height sensors. These codes show up as the car being unable to raise or level the body, or reporting a loss of pressure. On Model S and X this is a common age-related fault.
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.
Ride height sensors are measured to be in twisted or implausible state.
Implausible condition detected on rear right air valve circuit, possibly due to ECU hardware failure.
Implausible condition detected on front left air valve circuit.
Air compressor has reached its duty cycle (on time) limit.
Air compressor has dropped below its duty cycle (on time) limit, plus some hysteresis.
Air suspension leveling via the air compressor will be temporarily disabled until air compressor duty cycle drops.
Abnormal PWM signal received from front right PWM height sensor. More sensitive than other ride height sensor alerts.
Implausible condition detected on air compressor or air compressor relay circuit, possibly due to ECU hardware failure.
Implausible condition detected on front right air valve circuit.
Implausible condition detected on front right air valve circuit, possibly due to ECU hardware failure.
Air suspension system is operating under limp home mode 20 restrictions.
The ECU has detected an issue whose severity requires operating under limp home mode 20 restrictions.
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.