ABS Pump Replacement Mercedes-Benz S-Class W220

Last updated: October 24, 2026

This article provides instructions for replacing the ABS pump on a Mercedes-Benz W220 C215. The ABS pump is integrated with the ETS, ASR, and ESP hydraulic unit.

Before you start: read this if you have not done a hydraulic job before

This one is different from most jobs on this site, because the part being removed is part of the braking system and the car cannot be driven again until the job is finished properly. Two things decide whether it is a job you can complete at home, and both of them come after the unit is bolted back in rather than before.

A replacement hydraulic unit normally has to be matched to the car. The electronic half of the assembly is a control module, and a module that has come off another car or out of a box does not necessarily arrive knowing which car it is in. Expect the replacement to need coding or initialising to this vehicle before the system will come out of fault, and find out which applies to your unit before you order it, not after the old one is out.

Bleeding the ABS unit is not the same as bleeding the brakes. A pressure bleeder pushes fluid through the calipers, which gets the air out of the lines, but the hydraulic unit has internal passages and valves that ordinary bleeding does not reach. Clearing those takes a tool that can actuate the pump and the solenoids while you bleed. If the pedal still feels soft or long after a conventional bleed, that is usually air left inside the unit rather than air in the lines, and the answer is the tool and not more pumping.

A scanner that talks to the ABS and ESP modules is what reads the codes afterwards and, on the better ones, what actuates the pump for the bleed. A YOUCANIC full system scanner covers the reading side and the bidirectional tests. Be straight with yourself about the rest though: if you do not have a way to code the unit and to bleed it with the pump running, this is the point at which the car goes to someone who does, and it is cheaper to find that out before the brake lines come off.

	Disconnect the battery negative terminal. The battery on your S-Class is located in the trunk.
	Open the hood and locate the ABS hydraulic unit. The ABS unit is located behind the driver’s headlight unit.
	Unscrew all the hydraulic brake lines from the ABS hydraulic unit.
	Unplug the electrical connector from the ABS pump.
	Remove the bolt that keeps the ABS unit in place. Remove the ABS hydraulic unit.
	Bleed the brake system using brake system bleeder.
	Use a diagnostic scanner to clear the fault codes. Read our article Top 10 OBD II scanners for Mercedes-Benz.

Refitting, and what has to be true before the car moves

The steps above take the unit out. Going back in is the reverse of that order, with a few things worth stating because this is a brake job:

• Catch the fluid as the lines come off and keep it off the paint, because brake fluid lifts paint and will not wipe off a wing afterwards. Cap or plug the open lines rather than leaving them, and expect the reservoir level to drop.
• Start every brake line fitting by hand so the threads pick up straight, then tighten them to the figure in the service documentation for your model rather than by feel. A cross threaded or overtightened line fitting is a leak you will find at the worst moment.
• Reconnect the electrical connector and the battery, then top the reservoir back up before any bleeding.
• Bleed the system, then code or initialise the unit and clear the codes, in whichever order the tool requires.
• Do not drive the car until the pedal is firm and high, there are no wet fittings anywhere, and the ABS, ESP and BAS lights are out. Those three warning lights are the car telling you the systems are offline, and a stored fault in that assembly can take ESP and BAS down with ABS.
• Then test the brakes at walking pace somewhere empty before taking the car onto a road.

Related Part Numbers

• 0044314612
• A0034318712
• 003 431 80 12
• 0130108096
• A0044314612