Code APP_w315 was reported by the “Autopilot — application layer” controller in the car. The letter “w” in the middle places it among entries of the warning type.
The application layer of Autopilot. Drives adaptive cruise control, lane keeping, lane changes and sign recognition. Faults here usually mean an assistance feature switched itself off temporarily — typically due to poor visibility or incomplete camera calibration.
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.
Unexpected physical attribute detected for left pillar camera - no service action needed
This is a logging alert when DI (Drive Inverter) PMM state is active or logging
This alert is not set in HW2.0+ cars and is deprecated
Autopilot features are not available because ECU is in offline calibration mode
Offline Calibration file is present on disk
Remove offline calibration file
Autopilot unavailable or degraded
One or more of the messages in payload are missing
When AP starts receiving above messages
Autopilot functionality is not available
ALC unavailable due to blocked ultrasonic sensors
Fisheye camera is not calibrated
Fisheye camera is not calibrated when AP is engaged
Alert indicates autopilot board is operating outside of it's recommended temperature range
Autopilot board temperature falls below 0C or over 90C
Autopilot board temperature is in nominal range
New fisheye camera calibration values are available
(1) DI (Drive Inverter) MIA, (2) DI not responding to DAS AEB request, (3) DI AEB state FAULT
Clears ten seconds after GTW (Gateway) drive rails turn on
Radar ECU indicates errors in CAN messages
Condition specified in alert payload.
Depending on set condition, once radar's internal checks pass this alert is cleared
Messages from Electronic Parking Brake (EPB) ecu are missing on vehicle bus
One or more EPB messages on vehicle bus are missing
AP starts receiving EPB messages again
Indicates Gateway (GTW) ECU is MIA
GTW CarConfig and GTW chnm messages are missing
After AP starts receiving these messages
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.