Air Suspension Problem

[MrQ4.8is]

I recently purchased an x5 4.8is 2004 model a week later the air suspension inactive has come up, the car is high on the front left and the height adjust buttons green light has gone off but if you rest the fault via diagnostic computer it all starts to work suspension goes up and down but after about 30 miles inactive again the errors read are height invalid and something about a valve (can't find the paper I wrote the fault codes on).

Any advice like where the sensors are on the car what I should try first...

Mr Q

[EH6TunerDaniel]

Give us the code first.

[civdiv99]

Symptom typical of bad height sensor. These are user verifiable with a multimeter. Somewhere on here I put the pin codes and related. In a nutshell you have 3 lines for the air suspension. Ground, 5v source, and a variable voltage based on position. Runs between about 1, and about 4, volts.

Some height sensors also have outputs to the LCM for the HID aiming, so be cognizant of that of you have 6 wires vs 3 at a given connector.

You can disconnect the arm on the height sensor and back probe the wires easily.

If you have INPA it's easier since it tell you real time what the height sensor is reporting.

Typical fault is when the voltage for the height stays low and unchanging. Car tries to raise but voltage doesn't increase as expected. You get a fault.

Common reason for this is the shaft seal on the height sensor wears over the years, and water intrusion can occur. Then corrosion, then failure.

If you don't have a way to diagnose, and your symptom is suspension inactive and one wheel jacked up out of kilter from the rest, start with the easy to check item - height sensor on that corner.

If you have INPA, you can manually put the heights where you want them, then set it to ignore plausibility checks (or something like that; I forget exact terminology). This will keep the car at the height you set (assuming no leaks and stuff; it won't self-correct in this mode). That way you can drive around as usual every day until part shows up and you feel like changing it out. Then put it back into normal operation and clear fault. All happy.

By the way, this mode is the easiest way to experiment with different ride heights and stuff, too, since it's essentially full manual control.

[upallnight]

Originally Posted by EH6TunerDaniel

Give us the code first.

[Roman D]

Guys, i have a question - I. See treads about air suspension faults all over the forum but on other hand those who does not have issues dont say anything to countrweight, is air suspension really really problematic?

[civdiv99]

Originally Posted by Roman D

Guys, i have a question - I. See treads about air suspension faults all over the forum but on other hand those who does not have issues dont say anything to countrweight, is air suspension really really problematic?

I've taken the time to learn the various functions and so forth over time just out of interest.

I have had 1 suspension problem in 8 years. $65 height sensor. I personally don't consider that as problematic, so there's your counter.

The reason this comes up is because absent the time, resources, and desire to understand and deal with problems, the owner is otherwise at the mercy of diagnostic techs. Those who have good ones do fine. Those who don't spend money chasing causes and solutions via parts and labor.

The only actual part/assy tbat I would consider somewhat pricey is the compressor unit.

[Gregory891]

@ MrQ4.8is. Could you please confirm you have four wheel air suspension? Do you have any error lights on your instrument cluster? Have you read any fault codes (yet)? Front left corner is high, would you believe that the right front corner is at a normal height - as well as the rear corners? Have you checked the front suspension for damage - I am thinking the height sensors and the links from them to the struts?

All of the suggestions given previously are spot on - you need any of the various bits of software to read your car's code (been there, done that, it works and eliminates troubleshooting). The compressor is unlikely as your problem is specific to one corner, hence height sensor related or the air strut yourself.

Low risk and moderate expense to replace the height sensor. My X5 (rear air only) gave me a dash light. Plug in INPA and it told me the specific height sensor to replace (no guessing about air springs, compressor, leaky lines, etc). Useful technology, you simply use the tool that works with it.

[ouzo12]

Originally Posted by Gregory891

@ MrQ4.8is. Could you please confirm you have four wheel air suspension? Do you have any error lights on your instrument cluster? Have you read any fault codes (yet)? Front left corner is high, would you believe that the right front corner is at a normal height - as well as the rear corners? Have you checked the front suspension for damage - I am thinking the height sensors and the links from them to the struts?

All of the suggestions given previously are spot on - you need any of the various bits of software to read your car's code (been there, done that, it works and eliminates troubleshooting). The compressor is unlikely as your problem is specific to one corner, hence height sensor related or the air strut yourself.

Low risk and moderate expense to replace the height sensor. My X5 (rear air only) gave me a dash light. Plug in INPA and it told me the specific height sensor to replace (no guessing about air springs, compressor, leaky lines, etc). Useful technology, you simply use the tool that works with it.

What ride height did you set it at after replacing? I just had both rears replaced in my 2005 3.0 and set at 700mm but to me it seems like it looks lower and feels like i can feel all bumps on the road.

[trojanman]

Could someone please post a picture of the sensor, and it's location. This just happened to my car this morning. Thank you.

[jcorreanyc]

Guys, for anyone with an '04 and EHC2 suspension problems, the culprit is very likely your air suspension module or "brain". The '04s had a different part number, 37-14-6-758-452 which almost always failed over time. In '05, the module was updates with a new part which had new hardware and software numbers, 37-14-6-773-999. These were much more reliable.

Many of the unexplained problems with these systems are because of this older module. If all else is working properly (ride height sensors, pump, etc) and you still have problems, you should change this out. I did on my '04 and haven't had a single problem since.