DML939

I have the obdeleven but I have not seen anything come up with the suspension in a scan

MP4.2+6.0

Address 34. You'll see it in many of the inane full scans folks post at times. See Level Control Bleeding/Charging - Ross-Tech Wiki


An excerpt from one random scan I found from a quick search where the suspension had issues:

DML939

So yesterday i pulled the wheel liner so i could see the pump and block and both look fine ( i am going to rebuild the compressor regardless). I have no leak tested as i need someone else to hold on the compressor while i look for bubbles etc. When i bought the car the guy did say his mechanic told him there was a leak in the passenger side front so i will need to address that. When i jacked the car up to get the wheel off and then turned on the pump, i got the rear end to raise back up to normal but the front did not move at all. I now only have the yellow suspension light on the dash and not the green. I checked the fault codes (obdeleven) and all i got for suspension was fault code 01399 which is self-leveling suspension compressor relay. Not sure if this is the relay under the dash i was manually activating or if its a different relay i need to check. I just cannot figure out why the relay does not activate on its own and i read everything i found on here in regards to suspension. Also im not sure why it seems like the front suspension isnt even getting any air. I know there is a leak but should it not try to lift up alittle especially on this side where there is no leak? Or is this a level sensor issue?

MP4.2+6.0

There is only one suspension relay, so hopefully you found the right one. Search on it if you need pictures and are not 100% sure you have the correct relay. It was actually in two locations. Many like mine are under the dash as part of a relay panel and very close to where its 40A fuse is located. Some are under the top part of the carpeted area IIRC.

If you have a big leak, the front is not going to go up. The two sides are tied together by the sway bar anyway--which forces both sides down even when the car can pump up but then the air leaks from one side. I suppose you can try disconnecting sway bar temporarily to see if at least one front corner will then move up some. No one has ever tried to diagnose that way AFAIK, but it is logically just the reverse of trying to diagnose when both sides seem to come down at same time when only one side leaks. Just do it at one of the U shaped sway bar end links with the single bolts. From your description of a likely bad passenger side strut, try disconnecting on driver's side. No guaranties, but you might get some comfort if one side does come up in front.

And yes, look for broken or disconnected level sensors just in case. They are right there on the lower suspension arms in front. You should easily see them when looking at the sway bar ends. They rarely seem to fail. Most reports find them somehow mechanically unclipped or with broken arms--typically from repair mistakes or road hits/damage.

I can't separately comment on OBD eleven since I don't use it.