Code PCS_a102 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.
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 got reset or powered cycle unexpected while it is commanded to perform DCDC operation
High DC offset present on charger input voltage sensor when voltage is not expected
Charger line voltage sensor DC offset exceeds threshold for more than five seconds
Charger line voltage sensor DC offset is below clear threshold for more than 500ms
PCS DCDC tank voltage sensor's DC offset exceeds threshold while DCDC converter is inactive
DCDC converter tank voltage sensor's DC offset exceeds threshold while DCDC converter is inactive
DCDC converter tank voltage sensor's DC offset is within threshold while DCDC converter is inactive
Pedal Monitor Warning: Torque Intervention.
The safety monitor sets this condition and indicates diagnostic information in its payload for root cause analysis.
This alert will clear on the next drive cycle.
The safety monitor will inhibit torque and excess heat production for the remainder of the drive cycle.
Pedal Monitor Warning: DI and PM versions do not match.
This condition is set when the inter-process communication version between DI and PM is mismatched.
Prevents DI ECU from booting, presents itself as a complete inhibition of drive unit capability.
Pedal Monitor Warning: Parking Brake CAN node is missing.
The safety monitor sets this condition when CAN communication from Parking Brake CAN node is considered irrational or missing.
Parking Brake CAN node is considered not communicating on CAN for remainder of drive cycle.
Pedal Monitor Warning: DIS CAN node is missing.
The safety monitor sets this condition when CAN communication from DIS is considered irrational or missing.
DIS is considered not communicating on CAN for remainder of drive cycle.
Pedal Monitor Warning: Crystal oscillator inactive.
This condition is at application boot when the external crystal is not the active clock source.
This alert does not clear during a power-cycle.
Unit cannot produce torque with this alert present.
Pedal Monitor Warning: CAN hardware error.
This condiiton is set when CAN peripheral hardware indicates an overrun or transmission error on the secondary CAN bus.
This alert will clear when CAN communication is re-established.
No immediate impact, may lead to indicating an MIA condition for the specific CAN ID listed in alert payload.
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.