Greetings, all!

I was driving yesterday on a back road and positively nailed a large bump (not a hole) in the road. Primary impact was driver's side.

Shortly afterward, the ASF warning popped up in the message center. When I left home this morning, it was still on and the pump wouldn't kick on. The front was quite low (not uncommon, as I have a very slight fitting leak) and never filled. I tried several restarts and no success. Once I got to work, I disconnected the battery for several hours. After reconnection, no success.

Could hitting a large bump cause a massive fault to the relay or the leveling switch or something else like that? I haven't had any problems (aside from the slight leak) with my suspension before. And the ASF warning only popped up after the bump. It isn't cold here in Western PA yet.

Thanks in advance for your help!

 

Hi Paradigm,

The first things that come to mind are that possibly the air bladder in the front driver's side air spring/shock ruptured, or the height sensor was damaged. I think you'll have to begin with a good visual inspection to see if there is any obvious damage. Sometimes when the air bladder ruptures it punctures a hole through the corrugated plastic dust gaiter on the shock, which will be an obvious clue.

Please let us know what you find.

Cheers,

Don

 

Has the front collapsed completely ? If not, then it suggests there is not a large rent in a front air spring bladder, as no compressor could possibly keep up with the air loss. There could, of course be a small but significant leak that is such as to need the compressor to keep running. If it runs for about 2 minutes without charging the reservoir to the correct pressure you get a fault flagged up. So best to get the codes read to see what it might be, plus a visual inspection of the suspension. A height sensor may have got damaged too.

 

The front end is all the way down. The "down"side to that is my existing slight fitting leak. It normally goes down overnight, but shortly after starting my car, the compressor kicks on and fills up the struts.

The compressor isn't turning on at all, which leads me to think the height sensor was damaged. Without it running, I can't diagnose any leak issues.

Could a damaged sensor keep the compressor from turning on at all? Could a strong hit of a bump blow out the relay?

I'll check out the car tomorrow. It's raining outside, and as low as it is, I can't check it out now...

Thanks again, folks!

 

Except for the very early X350s, most have only one front height sensor, on the left side (not sure if that is different in RHD markets). Since one height sensor determines the inflation / ride height adjustment for both front corners, it does seem possible that a damaged height sensor could be telling the Air Suspension Control Module (ASM) that the front end height is correct or even too high, preventing the system from sending more air to the front.

Ordinarily, the compressor will only run if the system pressure falls below a certain threshold, then it runs to replenish the pressure in the reservoir, and then only at startup or when moving at 25 mph or greater. I wonder if the electrical connector on the compressor or the Air Suspension Relay in the front engine bay fuse box might have been bumped loose? There's a pressure switch on the valve block in the trunk under the spare tire that tells the ASM when the pressure falls below the threshold and needs to be replenished by the compressor.

Sorry for the random thoughts. I hope you'll be able to examine the height sensor and air spring tomorrow and let us know if you see any obvious damage.

Cheers,

Don