Can anyone give me a rundown of the common ABC problems and potential fixes? Is it just the Pump you have to worry about, or do you need to worry about the other components as well? How about the model years, does it matter, are some better than others?

 

The easiest and cheapest fix, is the expansion hose, yes they do leak at any time, should be checked 1st, before you get a fancy bill from a dealer.

I believe the ABC pump and block valves were changed by 2004.

 

Where is the expansion hose located? I thought I had a leak in my valve pressure assembly behind my front left tire. I peeled the wheel well liner back and the assembly was bone dry, and one of the hoses has some oil residue coming down to the bottom of it. It's the hose that goes from the pressure assembly to a fitting just next to the strut. Look fairly straight forward. Did I just get lucky?!

 

This is EXACTLY where my 2003 SL 500 ABC suspension is leaking from. I have determined that it is the B4/5 pressure sensor for the ABC system. Have you had any luck finding a part number or a cheap fix?

 

Yes. Had the hose replaced, system flushed and Rodeo test. Local MB parts counter had an exploded view of the system and identified the hose.