Cayenne air suspension level sensor fault

[davek_964]

I've had this for 3 or 4 weeks now - initially it was fairly intermittent (for some reason, it rarely came on in the morning, but always triggered immediately when I was leaving work) - but now it's constant, and can't be cleared.

Air suspension failure / workshop shows up on dash. Durametric says it's a front left level sensor problem.

I initially checked the connector, sprayed it with WD40 etc - but it looked very clean anyway. I've now changed the sensor and that has made no difference at all.

I suspect a wiring / connector fault even though there is nothing obvious wrong - I will take another proper look at it this evening (knew I should have left the wheel arch liner off last night!). I don't really expect to find anything though, since my cursory check yesteday found no sign of problems at all.

The other slightly odd thing is that - after changing the sensor last night, I tried logging the output from all 4 sensors - and couldn't get anything out of any of them.

Thought it was worth a post in case somebody has had a problem like this before and solved it. If I don't find the cause this evening, I guess it will be heading to 9E shortly.

[davek_964]

Lemon yella RS said:

Not sure about durametric software but you might have a actual values page, the sensors voltages can be displayed. On mine i have three at approx 2.4v and one showing 0v, a possible clue. I guess you could check voltages at the plug to confirm they are there. It's a three wire device, so most likely ground +5v and signal . I have exactly the same issue. Front left. Will try to update this thread when i have it sorted.

I will try logging values again to see if I get anything.

I asked on another forum, and have been told the control module is in the boot panel on the drivers side - the silver box with two big connectors on it. I've toyed with the idea of unplugging it to see if there were loose connections, but it doesn't look like it's a harsh environment so reluctant to do that in case it causes other problems.

I think I am reaching the point where it's going to get dumped on 9E.

[davek_964]

Lemon yella RS said:

Forgot to add. The sensor may have to be calibrated when a new one is fitted. There is a set of measurements and procedure to follow. Google is your friend there.

Yep, I know it has to be calibrated - I'm assuming that it wouldn't cause a permanent fault if it hasn't been though - just a slightly incorrect level. Of course, I could be wrong and it may be that replacing the sensor has actually fixed it but the warning is due to lack of calibration.....

[davek_964]

Mine may get a proper check over on Saturday. I needed some unexpected maintenance on my 360 yesterday evening, and while that was being fixed I mentioned my Cayenne problem and although he specialises in Ferrari (and anything else that interests him) my mechanic said he also has full Porsche diagnostic kit and would be happy to take a look at it on Saturday if he's around.

I'm not really expecting a quick fix, but I'm pretty sure he'll make more progress than I have!

[davek_964]

Pope said:

New sensors have to be comissioned prior to reaching full functionality; you may also have HBA faults as the sensor is shared between both systems.

Can you clarify what "commissioned" means? (And what is HBA?)

I gave up and took mine to the mechanic. They checked continuity of all the connections and found no problems - and therefore concluded it must be the control unit.
They ordered a new control unit - and apparently it comes with 4 new level sensors. The new control unit did not recognise any of my old sensors, so they had to fit the new sensors (which obviously includes replacing the front left sensor I'd already replaced).

I've been told that this has solved the problem.

However, something doesn't sound logically right about this to me. If a new control box does not recognise any of the existing sensors - then is it surprising that the old control box didn't recognise the new sensor I fitted on front left?

What does "commissioning" mean with these sensors? Once I'd fitted a new one on the front left - did something have to be done to make my old control box recognise it?

Edited by davek_964 on Sunday 27th July 15:40

[davek_964]

OK - had a chat with 9E about this.

He said they had previously spoken to Porsche and were told that the control unit + sensors comes as a kit because it's changed for the newer Cayennes. Which I guess is why my old control unit didn't recognise the new sensor - and why the new control unit didn't recognise the old sensors (although I'd have thought it should have recognised the new front left).

But this suggests that if you do think a sensor has failed, you need to be careful about just buying a new sensor - because it may not work with the control unit if your car is old like mine. Seems I wasted the cost of a new sensor - which ironically, was half the cost of control unit + 4 sensors.

[davek_964]

thegoose said:

So if you'd bought a used sensor from a similar age car would that have worked (and saved you a small fortune )?

It would seem so, but I had no idea that a new sensor didn't work.

The good news is, although I haven't collected the car yet I asked for the total and it was quite a lot less than I expected. And I suppose at least I now have a spare front left sensor in case I ever need it.....

It is going to be an expensive month though. When I collect the Cayenne, I'll be swapping it with the turbo since that's due a major. And by the time I get that back, it will be time to renew insurance on all 3 cars