Code RCM_a049 was reported by the “Airbags and restraints” controller in the car. The letter “a” in the middle places it among entries of the alert type.
The Restraints Control Module — the controller for airbags, seatbelt pretensioners and crash detection. Codes in this group should never be ignored: they can mean an airbag will not deploy in a collision.
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.
There is a fault with the right C-Pillar impact sensor.
The restraint control module is not armed.
The restraint control module is armed.
The restraint system will not function as designed.
There is a fault with the left hood actuator.
There is a fault with the second stage of the driver airbag.
There is a fault with the front-right seat airbag.
The reprogramming limit has been exceeded.
Left vehicle controller CAN communication fault.
No left vehicle controller CAN communication fault present.
There is a fault with the Emergency Notification Signal-1 line.
There is a fault with the front-right impact sensor.
There is a fault with the second row right-side pretensioner.
There is a fault with the driver knee airbag.
The safety system has observed an impact.
The yaw rate inertial measurement unit is faulted.
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.