Windshield Washer Pump Replace

Brand: Mercedes-Benz
Model: S550 4Matic
Chassis: W221
​Engine: M278
Project: Repair
Labor: 1 hour


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The Windshield washer fluid pump is provided power to spray washer fluid on the windshield. As washer pumps get old or defective by an electrical surge, they can not provide the power to wash the windshield. An obvious indicator that your washer pump is failing that with normal washer fluid capacity, when you press the switch of the washing windshield, there is no washing fluid spray out. Btw, the windshield washer pump was controlled by the SAM control unit, there is no fuse for the pump. So there will no indicate on the dashboard, also no failure code was saved.


1, Washing water reservoir

2, Windshield washer fluid pump


Step 1  Open The Engine Hood


1.1 Pull lever in left side of footwell to unlock the engine hood. The engine hood jumps open; lift engine hood slightly if necessary;

1.2 Pull out handle and lift to open engine hood. (Windshield wiper arms must not be folded forward).

Step 2 Make room for replacing washer pump


2.1 Remove the frame seal in area of washer fluid reservoir;

2.2 Remove the engine's middle cover;

2.3 Remove the engine's right cover;

2.4 Remove the intake duct of connecting to the air filter housing.

Step 3 Unfasten the washer fluid reservoir


3.1 Suck out most of the washer fluid from the reservoir.

3.2 Remove the purge valve from the bracket;

3.3 Unclip coolant lines from the wheel well, remove heat exchanger from washer fluid reservoir, and place to one wide with coolant lines attached.

3.4 Remove the bracket which supports the purge valve;

3.5 Remove the nut which secures the reservoir.

Step 4 Remove the washer pump and replace


4.1 Remove the electric connecter of the headlamp washer pump;​

4.2 Remove the headlamp washer pump Pushing the pump bottom from the inside of the reservoir;

4.3 Disconnect the outlet hose from the headlight washer pump Beware, remove the clip first;

4.4 Lift the reservoir and remove the windshield washer pump;

4.5 Replace the defective windshield washer pump.

INSTALL in the reverse order

Key Step  Install the headlight washer pump and adjust the windshield spray nozzles


1.1 It's slightly different. Install the washer pump on the reservoir first, and then use Long Reach Nose Plier to install the washer outlet of the headlight washer pump in a tight space;

1.2 Adjust the angle of the windshield washer nozzle as diagram.


Windshield washer fluid pump: A 221 869 01 21

Windshield washer fluid: MB-Approval 371.0