Code APS_w041 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 APS fails to receive one or more CAN msgs from EPBL on Vehicle Bus
APS fails to receive one or more CAN msgs from EPBL on Vehicle Bus
APS starts receiving all CAN msgs from EPBL
Warns if APS fails to receive one or more CAN msgs from VCLEFT on Vehicle Bus
APS fails to receive one or more CAN msgs from VCLEFT on Vehicle Bus
APS starts receiving all CAN msgs from VCLEFT
Warns if APS fails to receive one or more CAN msgs from Primary EPAS3 on Party Bus
APS fails to receive one or more CAN msgs from Primary EPAS3 on Party Bus
APS starts receiving all CAN msgs from Primary EPAS3
APS doesnt receive EPAS msgs for more than 10 cycles
APS starts receiving msgs from EPAS
SMS/SMS UART communication failure
ACC Unavailable - Camera Blind
APS doesnt receive DI msgs for more than 10 cycles
APS starts receiving msgs from DI
Warns if expected park ecu fw version does not match the actual park ecu fw version
Expected park ecu fw version does not match the actual park ecu fw version
Park ecu fw is updated to match the expected park ecu fw version
Autopark and summon functions will be disabled
Warns if Primary autopilot fw version doesnt match the APS fw version
Primary autopilot fw version doesnt match the APS fw version
APS and/or APP fw is updated to match the vehicle fw version
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.