Code ESP_a186 was reported by the “Stability control and ABS (ESP)” controller in the car. The letter “a” in the middle places it among entries of the alert type.
The electronic stability program — ESP, ABS, traction control and brake force distribution. These codes show up as warning lights and some assistance systems dropping out. The car still brakes, just without electronic help.
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.
Invalid Brake Pedal Status received from CAN(Signal: BrakePedalApplied_Q)
iBST_brakeAppliedQF is invalid
Invalid Data Received From Drive Motor Control Module B: Data Length Code, Checksum or Parity invalid
Steering Wheel Position Sensor: Plausibility fault
The monitoring checks for a physically plausible steering angle signal and consists of following parts:- Sas range monitoringReceived raw sensor hardware value is higher than the maximum, physical steering wheel turn from zero-position to lock in the vehicle (LwAnschlMax) + an additional robustness tolerance value (typical 90 deg)- Sas gradient monitoringIf the signal gradient (steering angle velocity) from one 20 ms-cycle to another is higher than 40 deg for 2 SAS Messages (60 deg for more than 2 SAS messages or no SAS message counter) or - change of this gradient (steering angle acceleration) is higher than 30 deg a failure will be set.- Sas plausibility versus yaw rateThe difference between measured steering angle signal and model value calculated from yaw rate signal is evaluated for fault detection. Dependent on the driving conditions failures in size of (10 + 60 [m/s] / velocity [m/s]) deg at steering angle are recognized through three possible recognition paths evaluating stable driving conditions. This is to prevent a fault recognition due to unstable driving.When the difference is caused by a fault of the steering angle sensor a steering sensor angle fault will be entered. The sensor - yaw rate sensor(YRS) or steering angle sensor(SAS) - showing the largest deviation to the reference yaw rate is marked as faulty.
ESP detected vehicle skidding with locked wheels
Internal electronic fault detected on USV valves.
The unit has detected an internal fault in the USV valves or valve controls
Invalid Data Received FromBrake Booster iBooster : Invalid Signal Status.
IBST_pRunout is invalid on CAN
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.