Mercedes-Benz 420SEL Windshield Washer Pump Replacement Cost

Windshield washer fluid pumps are diagnosed by a guided process of elimination, from most likely, to least likely. The fuses are checked first, then the power at the windshield washer switch, then power coming from the switch, to the washer fluid pump motor. If there is electrical power going to the windshield washer fluid switch, but the switch will not send power to the windshield washer pump motor, the switch or wiring must be replaced. If the switch sends power, but the windshield washer pump will not run, power at the windshield washer pump would be checked. If electrical power reached the pump motor, but the motor did not run, it would be bench-tested, and confirmed failed.

To replace the windshield washer pump motor, the reservoir must be accessed, as it is normally installed in, on, or near the windshield washer fluid reservoir. The fluid reservoir can be installed anywhere on a vehicle. They are commonly seen under the hood, behind the fender wells, behind the bumper yet in front of the core support, or, of all places, in the trunk. Once it is located and accessed, the old pump will unclip, or unscrew, and the new will go on in reverse order. Once the washer fluid pump is tested, the vehicle can be reconstructed.

Some windshield washer replacement pumps do not come with sealing washers provided, and the technician may re-use or replace the sealing washers. We recommend replacing the sealing washers if the manufacturer specifies this as part of the procedure. If there is no guidance, changing the seal is the best choice

In most cases, a technician will charge a diagnostics fee for testing the system, and determining the windshield washer fluid pump is faulty. This protects the customer from needlessly replacing a properly functioning component.

Testing and replacing the windshield washer pump is simple on most vehicles, and access is generally small but sufficient. Ensure that the motor is tested from an external power source to test functionality, even if diagnosed faulty. If the pump is too difficult, or requires deconstruction to access, consider contacting a certified repair facility.