Code DI_a237 was reported by the “Drive inverter” controller in the car. The letter “a” in the middle places it among entries of the alert type.
The Drive Inverter — the power electronics that drive the motor. Codes from here show up as reduced power, a message about limited acceleration or, in worse cases, an inability to drive. Temperature codes are common too: the inverter protects itself under sustained load.
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.
Drive Inverter Warning: Non-zero accelerator pedal position detected while brake pedal is pressed
Drive Inverter Warning: Memory check error
Drive Inverter User Alert: This alert is set when pedal monitor requests drive inverter to shift into non-torque gear at low speeds
DI receiving shift request by PM at speeds below 1 MPH
DI exits park gear or 5s elapse in park gear or accel pedal press in NP alert occurs
Drive Inverter automatically shifts to park without user request
Drive Inverter Warning: Front drive unit disabled
Fault detected in the front drive unit
Fault in front drive unit is no longer present
Unable to produce any torque or power on the front wheels
Drive Inverter Warning: Park Brake detected skid during Selfpark
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.