Code APS_w219 was reported by the “Autopilot — secondary processor” controller in the car. The letter “w” in the middle places it among entries of the warning type.
The second, supervising processor inside the Autopilot computer. It checks the primary processor's work and guards safety functions, chiefly automatic emergency braking. Codes from here often accompany APP codes and clear once camera calibration finishes.
The car is flagging that something is not right. Driving is usually still possible, but some function may be limited.
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.
Warns if expected radar fw version does not match the actual radar fw version
Expected radar fw version does not match the actual radar fw version
Radar fw is updated to match the expected radar fw version
APS does not receive one or more msgs from SDM/RCM for more than 10 cycles
Clears when SDM/RCM msgs are received again
Features that depend on SDM/RCM msgs will be disabled
Warns if APS fails to receive one or more msgs from Backup Autopilot
APS failed to receive one or more msgs from Backup Autopilot
APS starts receiving all msgs from Backup Autopilot at expected rate
Body Controller missing in action
APS does not receive one or more msgs from Body Controller for more than 10 cycles
Clears when Body Controller msgs are received again
Features that depend on Body Controller msgs will be disabled
Warns if APS fails to receive one or more CAN msgs from RCM on Party Bus
APS fails to receive one or more CAN msgs from RCM on Party Bus
APS starts receiving all CAN msgs from RCM
AP features will be disabled since APS forwards these msgs to radar
Warns if APS failed to initialize the ethernet switch correctly
Ethernet switch programming fails or returns error
Ethernet switch is correctly initialized
AP communication over ethernet will be broken
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.