Help - car has died.... ECU ??
 

Hi all,
Travelling along this morning and the oil level light popped on. So I stopped,topped up the oil but the light remained on. Definitely enough oil as read on the dipstick so thinking a faulty sensor I continued on my journey. About 20 miles later in traffic, just shunting at low speed and the car suddenly died. When attempting to restart it I had all the gears ( D,R,1,2,3,4 etc ) all lit up red. Engine management light and abs light also permanently on, it turns over but won't fire up. Just had fault codes read and the gearbox is saying missing command from ECU, Engine says missing command from ECU and any attempts to connect to the ECU directly fail ?? I've been told by a local garage that an ECU fault is plausible.
Does a faulty component on the ECU seem likely ?? After my alarm horn exploits I'm quite keen to try to repair it myself as I've heard there can be problems with drains blocking and water getting in there, does this all seem plausible to you knowledgable bods ??
Worst case scenario I understand I'm looking at the best part of 1K to get a new one and I've seen some A8 ECU's on A8parts - Does anyone know if these are different units or are they just generic ECU's flashed with a different program ??
any help/advice from you chaps is much appeciated as I'm feeling really deflated now and IF there is a good time for car problems it certainly isn't 2 bloody weeks before xmas :-(
Help .... :rolleyes:

If You cannot connect to ECU then it sounds like ECU or wiring/power problem. Which car is it? I have spare ECU for PF S8 AHC engine. I can also adapt immobilizer to accept new ECU if You are local.

Its a 2000 facelift S8... can't remember the engine code off hand.
I'm guessing the drain plugs have been blocked earlier in the cars life resulting in water getting at the ECU. Its annoying cos I'm really on the ball at keeping them clear since I've had it.
Whilst waiting for recovery it did start on one occasion,ran for about 5 seconds then died again. With my electronic mind that just shouts dry solder joint to me, some kind of intermittent contact. My garage are going to get it out and try rebooting/reprogramming it but if that fails I'll have a look myself and see if there's any obvious pcb damage/dry joints/blown components etc
Cheers for the offer tho mate+++ - You wouldn't happen to know if the ECU is different between models then would you ?, Would there be a difference between the FL A8 4.2 ECU and the FL S8 4.2 ECU ??:Confused:

Yes, there are lots of different models of ECU out there. There will be a part number on it if you give me that I can find any alternatives for you.

I've left the car with a garage so can't get to it to read the code - will it not be the same for any other 2000 FL S8 ?

I have found 5 ECUs for the AQH and 9 for the AVP engine you might have in a 2000 FL S8.

ahhhhhh !!:rolleyes:
Its an AQH so that narrows it down a bit I suppose - I'll find out the code when the garage gets it out ( and asks me to bend over :tuttut::o )

If you change the engine ECU, you need to recode the immobiliser on a 2000 car as it is bult into the keys, instrument cluster and Engine ECU....

As far as I'm aware, this is an Audi only job. They're unlikely to be happy to fit you a 2nd hand ECU and code it, but in my experience if you fit it, then tow it to Audi and claim your car 'wont start' they should code it up.. ...ah hem...

unless you're real pally with the service manager in which case he might be more receptive to what you need..

I was pretty sure the oil level sender went direct to the instrument cluster though, not via the engine ecu, so it flagging up an error, wouldnt really tally with an engine ECU fault...

Wonder if the gearbox ecu has gone.... its odd that its lit up all the lights like that.... Much easier to change over the gearbox ecu, just plug and play... no coding to worry about... +++

cheers for the info IT.
If the gearbox ecu had died would I still have a problem connecting to the main ecu ?? As I can connect to gearbox and engine and they both chuck faults about missing command from main ecu??
As to it being an audi only job to recode the immobiliser would noone else be ablto do this. From online research there are companies that will repair/rebuild/reflash the ecu's and my local 'audi approved' garage made no mention to this being an issue......
Also I've been thinking, would the differing part numbers for the ecu's just account for a different program installed?, so the physical circuit board itself is identical and the presence of a certain program denotes the part number??

Ben at Shark Performance can do a lot with immobilisers and things only Audi 'should' be able to do, sorry to hear about your problems. I'm sitting in a hotel in New York, havent seen my 8 in two weeks but it will be waiting for me at Heathrow this weekend for a nice blast home, looking forward to it!

You have just triggerd a thought. Whose lead are you using for diagnostics? VagCom (VCDS) or the full Audi lead?

If it's a VagCom lead it might be out of calibration as I had a similar issue with an ECU. My VagCom lead would not read the ECU but a mates would. I e-mailed Rosstech, they had me do a diagnostic with the debug facility set at 8. I emailed them a couple of files this generated and the e-mailed me back a calibration file that reset my lead and hey presyto I could read my ECU again!!! :)

If it's a vagCom lead (genuin RossTech) then it may just need calibrating.

What do you mean with main ECU? ECU stands for engine control module. You say You can connect to the engine and gearbox ( TCU- transmission control unit). What is the fault codes and what are You using to get the fault codes?

I'm not sure what lead was used but I'm almost certain it'll be a cheap one! The first garage gave me the errors printout but the garage its with now seem really knowledgable - they tend to do mercs/Bm's/audis ; they had a fat v12 merc in bits so gave me some confidence. They do a lot of remapping so they use the leads quite often - I'm sure they'd know if they're lead was dodgy. They probably won't get to look at it til friday so I'll keep you updated .
I've also found a place called ecu doctor that can test/repair the ecu for about £150 - no fix / no fee...... Sounds promising, if indeed it does turn out to be the ecu. I guess its quite hard to diagnose without putting a working ecu in although I presume you can check the power input line to the ecu is correct......
Really having doubts about S8 ownership at the moment, got no spare cash right now and can jst about afford to run it nevermind big repair bills....oh well

I've used the ECU doctor when my Mitsi Pajero (V6 Petrol) ECU went AWOL, had it turned around in about 3 days (by post) He's happy to talk about solutions on the phone
Did a splendid job on my Mitsi ECU, it came back much more economical, more power & better acceleration than it had ever been in my previous 8 years of ownership..... came to £180.00 was well pleased.

Hope this helps you daz

My garage has confirmed the ecu is at fault - was full of water apparently and damaged beyond repair.....
They quoted £870 all in for a new one, might just do that cos its hassle being without a car if I tried ecu doctor, especially over xmas. I am worried about possible issues with the immobiliser and keys etc as these all need go be sinked up don't they??
I understand the drain lines can be the cause, sure I've seen a fix somewhere but buggered if I can find it now - does anyone know of a link ??
Would't want it happening again......

Hi had that problem myself with the drain plugs

Try thishttp://audi-diy.blogspot.com/2007/11...or-drains.html

I just looked at Elsawin and ECU adaption procedure is the same as for prefacelift You do not need logins or anything for it. Fairly simple to do. keys are coded to immobiliser so You will not need to recode keys only need to do adaption for immo to accept new ecu.

£870!!!!

If you have the ECU part number, A8Parts may be able to help. If not with a part number I may be able to get one cheaper.

cheers conan, I've had the new one fitted cos I needed it sorted for xmas and all is well again......except the bloody radio is asking for a code now which I havn't got.
The stealers want £15 quid to tell me, does anyone know now I can get it for free ??

Glad it's sorted Daz, might be worth looking into a warranty for the future if the costs are a concern. I would only go to Shark Performance for immobiliser,ECU & radio code retrieval depending on how far he is. I think £15 ain't a bad price mind you...
Also have they sealed up or stopped the issue that was letting the water into the ECU in the first place and if so where did it develop? It might be worth others checking theirs to prevent it happening in the future. +++

apperently they checked all the drainage holes which were fine and the only conclusion we came to was that when we had the recent snow I didn't drive the car for a few days and that cos I didn't clear the snow off the windscreen it would have melted down through and got to the ecu... Basically the case of the ecu is nowhere near watertight - it has a screw in each corner holding the two half's together. I wouldn't advise anyone to pressure wash their s8 engine thats for sure. ! On later ecu's there is a gasket around the lip of each half to help protect it.
The ecu itself had blown about a dozen components and all the contacts down one side of a chip burnt so I didn't really fancy a try at repairing that......
Just for info the garage I used was Kartechnik in Poole and I was really impressed with their knowledge, not cheap but really know their high end motors......
With the radio, I know man who knows a man who knows a man who knows an audi master tech who can apparently sort the code out for free, says its a 1 minute job. Unfortunitely its taking ages to hear back from him.......
So whats the deal with the warranty then?? - does it cover the gearbox as that is my main concern, and how much '£' would we be talking......

I hate to post this I really do but I did miss it....

The ECU's on the A8's are very simple to swap. Readapting into the instrument cluster with the older models as they run IMMO2 is very straight forward. Install the new ECU and the immo light will flash. Connect in VAGCOM/VCDS and go to Channel 17 to the Instruments. Goto Adaptation then goto channel 00. Read and save the settings. Ignition off for 10 seconds and then on again.

It's now done.

Alternatively you can swap the 4 pin chip over from the old one to the new ecu with the immo details in. Very simple to do.

Do bear in mind whilst the 8 was a £70k it doesn't thanks to A8 Parts and others have a £70k service tag anymore!!

Interesting Daz as my '98 A8 had a seal between the two halves of the ECU chamber. I wonder if someone has opened your and dumped the seal.

mine is sealed with some sticky paste