Dynamic damper failure EDCSVL, required to replace shocks in pair?
 

Another day another failure of some sort...

This time it is the dynamic damper system that is failing. I read out codes which said 00633C EDC SVL Control unit: internal fault. This is apparantly the front left damper satellite. As far as I can see it is one part with the electronics, part number 37116794531, at about a $1000. I would be fine with just replacing one shock now, but according to my source supplier it is required to replace both right and left. Anyone else heard that before? I cannot see any reason for that. As long as the shock is working I cannot see why it needs to be replaced in pairs. Either it works or not. It should not change characteristics during its lifetime as long as it is electronically controlled... Unless there is some coding procedure that prevents replacing just one?

I have AD and Load Level in my X5 and am tackling the rear bags tomorrow. My fronts seem ok and I just have one failed suspension bag in the rear but Im replacing them both just in case. The cost is low enough that I figured what the heck. You may just want to try replacing one and see what happens.

It is probably recommended to replace the shocks in pairs because one new and one with 50k or so miles will have different characteristics. You can replace one, both or dont replace anything. After my wife's '09 Z4 both front shocks leaked badly at 40k miles I decided that I dont need to spend $2k every 40k miles and just installed regular shocks and re-coded the car.

Air bags and shocks are not the same thing. Air bags are instead of coil springs (and you only have them in the rear, regular coil over in the front), and only inflated or deflated according to load (to keep the same height), the dynamic dampers are shocks with electronically controlled characteristics. And you have them both front and rear.

If you know both the air bags have been replaced at the same time and one is worn out, and you can see wear marks (cracks in the rubber) I agree that it is smart to replace both at the same time, but otherwise one can live for years, and it takes 20 minutes to replace. The only gain in doing both at the same time is the time it takes you to put the car on even stands so that you have the anti roll bar free on both sides.

I would never do that to the X5. It is a different car with dynamic/adaptive drive. The Z4 is a light car and it can handle well with normal suspension.

Anyhow, after some phone calls theres apparantly no reason to replace both at the same time. It seems like a dependency fault in my part suppliers system.