Code CP_a125 was reported by the “Charge port” controller in the car. The letter “a” in the middle places it among entries of the alert type.
The car's charge port — latch, connector lock, indicator light and proximity sensor. These codes typically appear when the connector will not lock or the car does not register that it is plugged in.
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.
The charge port is unexpectedly not allowed to use high power from LV bus
Charge port is not allowed to use high power from the LV bus
Charge port is granted permission to use high power from LV bus
Charge port latch, door, and inlet heater will not behave as expected
The charge port either timed out during a mode request or failed to enter the requested mode
Charge port detected a unexpected fast rise in temperature
Charge port thermal velocity (calculated each minute) exceeds the expected rise in temperature.
Once the charge cable is connected Thermistor is greater than the open circuit threshold and, if short circuit detection is supported, less than the short circuit threshold for at least one second
Continued charging may result in damage to the vehicle
The CP has detected a hardware condition that would prevent the microcontroller from going to sleep
The CP has detected that the Gen 2 Wall Connector has measured a temperature at which AC charging should begin to fold back
info from manualCP_A101
The Gen 2 Wall Connector reports a temperature greater than 80C
Charge Port door potentiometer damaged
info from manualCP_A043
The CP door potentiometer behaves erratically
The CP door behaves rationally through several door cycles
Charge port door may not open or close as designed
Cable proximity did not latch within the expected timeframe
Cable proximity remains unlatched for an unexpected long duration
Cleared when proximity changes from unlatched
The CP is unable to confirm the state of the charge cable
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.