What is the reason for the ABS and ESP lights coming on after a vehicle inspection?

[LaMartin]

Fault ESP indicates a no speed signal fault for the right front wheel; ABS, short for Anti-lock Braking System. Its function is to automatically control the braking force during vehicle braking, preventing wheel lock-up and maintaining a state of rolling and sliding (with a slip ratio of around 20%) to ensure maximum adhesion between the wheels and the road surface. Working principle of ABS: During braking, ABS quickly determines the lock-up state of each wheel based on speed signals from wheel speed sensors, closes the normally open input solenoid valve for the wheel starting to lock, and keeps the braking force constant. If the wheel continues to lock, the normally closed output solenoid valve opens, causing the braking pressure on that wheel to rapidly decrease due to the direct connection to the brake fluid reservoir, preventing complete wheel lock-up due to excessive braking force. This keeps the braking state at the optimal point (slip ratio S of 20%), achieving the best braking effect and the highest driving safety. Classification of ABS: ABS is mainly classified based on channels. In ABS, the brake pipelines that can independently adjust braking pressure are called control channels. ABS control channels are divided into four-channel, three-channel, two-channel, and one-channel types. One-channel ABS: Also known as single-channel ABS, it has one brake pressure regulator in the rear wheel brake main line and one wheel speed sensor installed on the rear axle differential (some have one on each rear wheel). Two-channel ABS: This type of ABS struggles to balance directional stability, steering control, and braking efficiency and is rarely used today. Three-channel ABS: It independently controls the two front wheels and jointly controls the two rear wheels based on the low-select principle (i.e., both wheels are controlled by one channel to ensure the wheel with less adhesion does not lock), also known as hybrid control. Four-channel ABS: It has four wheel speed sensors, with one brake pressure regulator in each of the four wheel brake pipelines for independent control, forming a four-channel control system.