Hello,
I have a 2003 clk 320 and I have an issue in the right low beam, I tried changing the bulb and the igniter but nothing worked, I checked the fuse it was fine and the malfunction shows the right low beam. so I believe that it's the ballast because the left one is working fine, but my question here is that if I can replace it with an aftermarket one or not?

The second thing is the windshield washer pump, when I press on the wipers controller it doesn't spray and the wipers don't move, but the wipers work normally and the rain sensor works.
When I checked for the fuse it showed "electronic".
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I changed my ballast two years ago with a cheap chinese one, no problems so far...

 

I had a ballast die on my old CLK55, picked up a used one off ebay (shared part number with the C class) for about $40 and it lasted over 10 years.
Good news is the passenger side ballast you can get at from under the car. The driver-side i had to pull the bumper off for.