Code HVP_w028 was reported by the “High-voltage protection” controller in the car. The letter “w” in the middle places it among entries of the warning type.
The high-voltage protection unit — battery contactors, current measurement and the HVIL safety loop that disconnects high voltage the moment a connector comes loose. These codes turn up after collisions and after service work alike.
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 the pack voltage doesn't match approximately with sum of brick voltages
The pack voltage doesn't match approximately with sum of brick voltages
The pack voltage match approximately with sum of brick voltages
The contactors may not be allowed to close
Alerts if PyroLeakTest pyro diagnostic has cross warning threshold
PyroLeakTest sees an Aout outside of 15% tolerance when measuring leakage
Customer Facing text to seek service immediately
Warns if the BMS node is mia on HVS CAN
The BMS node is mia on HVS CAN
The BMS node is not mia on HVS CAN
Warn if FC contactors are forced open
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.