What causes the ABS and ESP engine yellow light to illuminate in a Mercedes-Benz?

[StGideon]

Reasons for the ABS and ESP engine yellow light illuminating in a Mercedes-Benz: Dirty throttle body; Faulty brake switch and wiring; Malfunction in the intake system; Use of substandard fuel. Function of ABS: Maximize the effectiveness of the brakes, reducing braking time and distance. Effectively prevent vehicle skidding and fishtailing during emergency braking, ensuring excellent driving stability. Allow steering during emergency braking, maintaining good steering control. Avoid excessive friction between tires and the ground, reducing tire wear. Working principle of ABS: During braking, ABS rapidly determines the wheel lock-up state based on speed signals from each wheel speed sensor, closing the normally open input solenoid valve for the wheel that begins to lock, keeping the braking force constant. If the wheel continues to lock, the normally closed output solenoid valve opens, allowing the braking pressure on that wheel to rapidly decrease due to the direct connection to the brake fluid reservoir, preventing complete wheel lock-up from excessive braking force. This keeps the braking state at the optimal point (slip rate S of 20%), achieving the best braking effect and ensuring maximum driving safety.

[SanAlessandra]

Last time I drove a Mercedes, I also encountered the situation where the ABS, ESP, and engine warning lights all lit up simultaneously, which really scared me. Thinking carefully, when these three lights come on together, it usually indicates an issue with the chassis or engine system. The most common cause is a faulty wheel speed sensor, which is responsible for monitoring wheel rotation speed. If it fails, it directly affects the ABS and ESP systems. It could also be a problem with the braking system, such as uneven brake force distribution. Another possibility is an engine-related fault affecting the ESP control module—for example, an inaccurate mass airflow sensor can trigger the engine light and also impact ESP. It's crucial to use a diagnostic tool to check the specific trouble codes immediately, then decide whether to replace the sensor or repair the circuit. Never continue driving forcefully, as high-speed turns without ESP protection are particularly prone to loss of control.

[VanElisa]

Attention to all Mercedes-Benz owners: If these three warning lights illuminate simultaneously, there's an 80% chance it's a wheel speed sensor issue. I once encountered this during a long-distance trip - the car body shook violently with warning lights on. Modern vehicles are equipped with numerous sensors, with one at each wheel. Even a single sensor covered in mud or waterlogged can trigger errors. Another potential culprit could be a faulty ABS control module, which is quite expensive to repair. Also, don't overlook alternator problems, as voltage fluctuations may activate warnings. Immediately reduce speed and pull over, then try restarting the engine. If lights persist, seek professional repair immediately - dealership technicians can usually pinpoint the fault within five minutes using diagnostic computers. Parking away from water puddles can effectively prevent sensor water damage.

[Leila]

It's quite common for Mercedes to illuminate these three warning lights. A faulty wheel speed sensor is the top culprit, especially when driving in the rain as rear wheels splashing mud can easily clog the sensor. Additionally, not changing the brake fluid for too long may also trigger the fault, as the ESP system is highly sensitive to brake fluid levels. Sometimes it's just loose wiring—the rear wheel sensor connector getting jostled loose can also throw a fault code. The most troublesome issue is when the ABS computer malfunctions, which requires professional equipment to diagnose. It's advised not to tinker with it yourself; Mercedes' electrical systems are too sophisticated, and randomly unplugging connectors may cause new faults. The most reliable approach is to have a repair shop read the fault codes first.