Code PCS_a103 was reported by the “Power conversion system (PCS)” controller in the car. The letter “a” in the middle places it among entries of the alert type.
Had code PCS_a103 as well? Tell others how it turned out for you →
The Power Conversion System — the combined onboard charger and DC/DC converter. It handles charging from the socket and generating the 12 V supply. These codes mostly show up as slower or interrupted charging.
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.
PCS detected that the LV bus voltage enetered the foldback region during the HV bus precharge
PCS has detected at least one reset during the boot up process. AC charging power might be limited if phase damaged is detected
Power conversion system detected reset while enabling a phase
Reduced AC charge rate or inability to AC charge if pahse damaged is detected
PCS intermediate bus voltage behavior is irrational, may indicate a hardware issue
Charger detects phase temperature is high
Charger phase temperature exceeds derating start threshold for more than five seconds
Charger phase temperature is below derating start threshold for more than five seconds
PCS DCDC detects 12V bus voltage is higher than the safety threshold to continue its operation
DCDC converter detects that low voltage bus voltage exceeds overvoltage threshold
PCS detects grid frequency droop below a certain level
AC charging will be blocked to reduce load for the grid
Charger phase temperature is irrational
Charger phase temperature is outside expected range for more than one second
Charger phase temperature is within expected range
PCS does not receive CAN messages from UI
High DC offset present on charger input current sensor when charge functionality is not enabled. Indicates issue with vehicle if seen multiple times over multiple days.
Charger line current sensor DC offset exceeds threshold for more than three seconds while charging is inactive
Charger line current sensor DC offset is below clear threshold for more than 500ms
This part is written by you. If you have had code PCS_a103, tell us when it appeared, what brought it on and how it ended — for the next person, one such sentence is often worth more than the entire service documentation.
Be the first. A nickname and a few sentences are enough — they will make this page useful to the next person standing by their car with the same message.
No e-mail, no registration — a nickname and your text are enough. The comment appears straight away.
Comments are written by visitors to this site. They are not advice from Tesla or from TesList and we do not verify them — treat them as one person's experience with one particular car.
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.