A005431791205 | Genuine Mercedes Benz® Anti Lock ABS Hydraulic Pump

• Prevents Wheel Lock-Up

  • During hard braking, a wheel can stop turning (lock up) while the car is still moving.

  • The ABS hydraulic pump, controlled by the ABS computer, rapidly adjusts brake pressure to keep the wheel turning just enough for traction.

• Restores Brake Pressure

  • When the ABS valves release pressure to stop a wheel from locking, the pump quickly builds it back up.

  • Without the pump, your brake pedal would sink or feel spongy after ABS activation because fluid pressure wouldn’t recover properly.

• Maintains Steering Control

  • By preventing wheel lock, the pump allows you to steer around obstacles even while braking hard.

  • This is the biggest safety advantage of ABS.

• Improves Vehicle Stability

  • Especially on wet, icy, or uneven roads, controlled brake pressure keeps all wheels gripping as evenly as possible, reducing skidding or fishtailing.

The ABS light (usually amber) on your dashboard is the most common sign.
The car’s computer has detected a fault in the ABS system — often from the pump motor, solenoids, or internal pressure issues.
Sometimes the Check Engine Light or Brake Warning Light may also appear.

2. Brakes Lock Up During Hard Braking

If the ABS pump isn’t regulating pressure properly, your wheels may lock up during sudden stops — exactly what ABS is designed to prevent.
You might feel the car skid or slide, especially on wet or icy roads.

3. Unusual Brake Pedal Behavior

The brake pedal may feel:
Hard/stiff (pressure isn’t being released properly)
Soft/spongy (loss of hydraulic pressure)
Pulsating continuously, even when you’re braking normally (ABS pump cycling when it shouldn’t)

4. Brake Pedal or ABS Motor Vibrations

You might feel vibrations through the brake pedal (or hear buzzing) at low speed — this can mean the pump or valves are activating erratically.

5. No ABS Action in Emergencies

When the pump fails completely, the ABS system shuts off, and your car reverts to standard braking.
You’ll still have brakes, but no anti-lock function — meaning the wheels can lock during panic stops.

6. Grinding or Buzzing Noises

A bad ABS pump motor can make grinding, buzzing, or humming sounds under braking.
These noises come from the electric motor or internal valves sticking.

7. Inconsistent or Uneven Braking

The car may pull to one side or feel unstable when braking hard.
This happens when the pump can’t maintain equal pressure across all wheels.