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Discussion Starter #1
Before I start - I haven't run any VagCom tests yet - and fully realise that will probably give a definitive answer but since the problem occurred on the way to work - I can't use VagCom until tonight - and am very worried now!

One the motorway this morning, when the Q7 attempted to select the lower suspension profile at speed, the amber warning light illuminated and the esp button became "unavailable" - you cannot turn ESP on/off.

Once safely in the carpark - I tried a few things. After restarting the car, I can select Offroad or Lift - and the car responds. I can also lower the car to Comfort. Selecting dynamic causes the error to re-occur. I restarted, raised the car to comfort and then selected "loading mode". The rear suspension did not respond and the fault light came on again - so I guess I'm looking at some kind of issue with the rear suspension (valve, sensor?)

Any thoughts, chaps?
 

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Discussion Starter #2
As an addition - I just tried the "loading" button in the trunk. The light flashes - but the rear-end doesn't lower. :(
 

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One of the rear self leveling sensors is damaged.
The part number is 7L0 616 571 D. This sensors are mounted on the back of the wheels and are very exposed to moisture, water infiltration when driving on wet roads and damages due to small rocks thrown by the wheels .
I changed my left side sensor twice last year.

The sensor is not very expensive (about 130 euro in Germany) but the installation can be expensive as it will require the re-adjustment of the suspension levels.

To be 100% sure that the sensor is damaged you can observe the behavior of the headlights automatic adjustment. When you hit the brake with headlights ON, because the sensor is damaged, the Automatic Headlight Range Controller can not estimate the car's body attitude and can not adjust the beams. This will result in the reset of the headlight adjustment which is causing the beam to lower to the front of the car and then go up again searching for the default position. This will happen every time you hit the brake pedal.
 

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Discussion Starter #4
Neo

Thanks for replying. I hooked vagcom up and it logged 01400 and 02250?

I cleared the dtcs, and selected to drop the car for loading. The front axle lowered about 2", the rear axle didnt move at all - then the module threw the 01400 again.

Given that the 01400 represents the compressor is overworking??? Is this some kind of misinformation? I dont get why the compressor would be used to LOWER the vehicle.

Also, it looks to me like channel 4 on the result blocks shows ride height for each sensor. Two sensrs (i guess rear) showed +30->+40, the other two readings were -9->-15. However, if these readings ARE the ride height - as the car is driven up and down kerbs, te readings look plausible.

Given this information - are you still sure of the diagnosis of a rear sensor?

And the test for hitting the brakes, the car must be moving, yes? Any minimum speed for such a test?

Thanks for any help you can offer.
 

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Ch.4 is not the ride height.
Here is the Ch.4 explanation:
Measured value block 004:
- Deviation from standard level FL or 'default position not learned' (height deviation front left from standard level in mm)
- Deviation from standard level FR or 'default position not learned' (height deviation front right from standard level in mm)
- Deviation from standard level RL or 'default position not learned' (height deviation rear left from standard level in mm)
- Deviation from standard level RR or 'default position not learned' (height deviation rear right from standard level in mm)

The vehicle height is shown in Ch.5 as follows:
Measured value block 005:
- Vehicle height absolute FL
- Vehicle height absolute FR
- Vehicle height absolute RL
- Vehicle height absolute RR

The vehicle height deviation is measured in Ch.10 with the help of the sensors as follows:

Measured value block 010:
- Vehicle level deviation FL in mm
- Vehicle level deviation FR in mm
- Vehicle level deviation RL in mm
- Vehicle level deviation RR in mm

01400 error means that the control level is not reached. That can be caused by a leak in the system which will cause the compressor to overrun. You will have to check the entire system for leakage.


Can you please post the entire DTC shown by VCDS including freeze frame? It will help me to better understand the problem and help you.
 

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Discussion Starter #6
Thanks again Neo.

I don't have access to the car (or the logfiles from Vagcom) until this evening. I'll post back tonight.

I saw on ross-tech that 01400 can indicate a system leak - although it seems strange to me that if the codes are cleared and the "loading" level selected, the compressor does not start (nor is it needed) and the 01400 still occurs.... maybe it can also just indicate a failure to get to the selected height - and most times this is because the suspension has insufficient pressure to "lift" the car? For the record, my front suspension goes up and down just fine. :(

I'll get the logs and post - the only thing I remember is Freeze Frame: 66 at the bottom of the 01400.

Thanks for the support - anything you can suggest is welcome - with Christmas just ended I simply cannot afford to spend huge amounts of money on this. :(
 

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Discussion Starter #7
Something else that seemed strange now I think about it.

You know the way that certain ride heights are unavailable at certain speeds? Well - it all seems a bit "wrong" at the moment.

In the "fault" condition with the amber suspension light lit solidly; dynamic, lift and offroad are unavailable and greyed-out.... which seems fair enough. Except that "offroad" became available every time the vehicle speed exceeded 55mph (and was greyed-out again below 55mph).

This seems wrong?
 

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Discussion Starter #8
Neo...

This was the scan result:-

Address 34: Level Control Labels: NONE
Control Module Part Number: 4L0 910 553 B HW: 4L0 907 553
Component and/or Version: LUFTFDR.-CDC H03 7550
Software Coding: 0015510
Work Shop Code: WSC 31414 790 00001

2 Faults Found:

01400 - Suspension Level Control
001 - Upper Limit Exceeded
Freeze Frame:
Fault Status: 11100001
Fault Priority: 2
Fault Frequency: 2
Reset counter: 199
Mileage: 154728 km
Time Indication: 0
Date: 2011.01.04
Time: 06:24:06

Freeze Frame:
Error Code: 66

02250 - Function Deactivation; Valve Duty Cycle
001 - Upper Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100001
Fault Priority: 6
Fault Frequency: 1
Reset counter: 239
Mileage: 154730 km
Time Indication: 0
Date: 2011.01.04
Time: 13:54:02

Freeze Frame:
Error Code: 46
 

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Discussion Starter #9
I notice that the 01400 is followed with 001 - ULE. Most of the reports on the web appear to be 002 - LLE.

Could the 002 represent a vehicle on it's bump stops where the compressor cannot raise the car due to a leak and the 001 represent a vehicle which is too "high"?

I'll give up with the guesswork and wait to see if Neo has any ideas... but one other thing Neo - is it worth trying to run the sensor level calibration? I'm just thinking that during the initial two-stage height change prior to calibration, the rear suspension may lower itself?

Thanks (as always!)
 

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Looking at the error registered i can suggest the following:

1. check the system for leakage, a loose in air pressure can cause the valve unit in the compressor to over run, this is reflected by the second error code you get.

2. if the duct system is intact i will suspect that the solenoid valve unit itself is faulty. this is part. no. 7L0 698 014 and is about 350 euro.

You can check the valve unit only with the VAS diagnosis system by selecting the function : "bleeding and charging system", there is no way you can check it with VCDS.

There are several connection pieces on the air duct system, i will suspect that one is loosing air. In ELSA there is a written procedure how to renew the connecting pieces when "a leakage is detected".

I advice you to go to an Audi Service and diagnose the problem. You can not solve this in your garage, it can be a simple connecting piece failure which will cost few euro or in the worst case scenario can be the valve unit or the compressor itself in which case you can easily find a used cheaper one on the german ebay.
 

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Discussion Starter #11
Just what I didn't want to hear. :(

OK - I'll use soapy water to check for air leaks... other than that... off to the dealer. :(
 

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you will not have access to all the ducts and the connecting pieces to check them with soap and water, if you want i can help you with the ELSA extracts regarding the air ducts and the connecting pieces that you have to check for leakage. I will need an email address as i cant post them here.
 

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Discussion Starter #14
Well, the car is booked in to the local main dealer for next Tuesday. Here's hoping at £140 an hour it wont take them too long to make a definitive diagnosis. :(
 

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Discussion Starter #15
Good news?

OK - we continued diagnostic fault-finding... Neo, thanks as always for your help.

The suspension is now working as normal. No error lights, car goes up and down as normal.

Drove around over the weekend with no DTCs but on the way home from work today, the following DTC was logged:-

01577 - Turn-Off due to Over-Temp
001 - Upper Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100001
Fault Priority: 6
Fault Frequency: 1
Reset counter: 249
Mileage: 155051 km
Time Indication: 0
Date: 2011.01.10
Time: 15:07:00

Freeze Frame:
Error Code: 68

"Luckily" - this was the journey I had decided to run a final test and was logging key data from the level control module. I've attached the full logfile if anyone's interested - but here's my thoughts.

The DTC would suggest (according to popular opinion) that there is an air leak in the system and the compressor is overheating attempting to compensate.

However, the log shows that the compressor was started 1:25 minutes after I left work... this was around the time the car's speed went above 20mph. The system pressure immediately rose from 4.56 bar to 10.42 - but then something interesting happens.... Over the next nearly 2 minutes, pressure only rises another 5 bar... but the compressor temperature increases rapidly to a reported 231oC! This was the cause of the DTC above.

Even though the compressor soon cools (it reaches ambient temperature(isg) of 13oC after 15:01) it is not re-activated until 22:25 when it runs for 11 seconds reaching a temperature of 122oC. Incidentally, the log shows the car's ride height was being adjusted at this time.

And that's it.... the compressor is not needed again for the entire journey (80 miles) lasting 1:13:55.

This leads me to believe that the problem is the compressor - it is either "siezing" or in some other way suffering from extreme friction.

If the system was leaking air from a spring bellow - I'd expect to see one of the FL, FR, RL, RR valves being opened frequently to "top-up" the lost air in the spring.

If the system was leaking air from the accumulator or valve block etc - I'd expect to see the compressor being engaged much more frequently as the system attempts to re-pressurise the accumulator etc.

Is there an error in my logic? I'm debating ordering a new compressor...?

Thanks for any advice (or sympathy),

J
 

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Discussion Starter #17
OK - maybe it is a leak. :(

I know it's easy to say "take it to a dealer" - but at £140p/h - with no guarantee they'll diagnose the fault accurately - and parts at the dealer costing twice as much as the "real world".... :(
 

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Discussion Starter #18
Well, thanks again to Neo for all his help with this.

The car has returned from the dealer after they have run VAS diagnostics and they have concluded that the compressor is at fault and needs replacing.

Compressor £1700 + tax
Other fittings £ 120 + tax
Labour £ 360 + tax

So - the total cost from the main dealer is around £2600! For a car which is only a couple of months past it's 3rd birthday!
 

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i am sorry to hear that, you can find a used compressor at a decent price on the german ebay, i'll have a look and send you a link by PM.
In germany the air supply unit is 1,270 euro + vat (19%).
 

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Discussion Starter #20
I have found a compressor for £500 from a German seller with a very good feedback rating. He has confirmed the compressor fits the (4L) Q7.

I know that Audi recommend changing J403 when the compressor is changed - this isn't a problem...

But the dealer quoted for a "pipe" & "fitting kit".

I am waiting on a friend to supply me with an "exploded" view of the compressor assembly with part numbers to do a little more research.

Oh - and I'm expecting to find more problems when removing the compressor... I'm wondering if the drier is full of water and that water may have got into the compressor causing the early failure.

Thanks again Neo - you're a star! :)
 
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