Can't find this part

4.2 V8 40v biturbo - 450 bhp
4.2 V8 40v biturbo - 480 bhp (plus)
95ninety
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Re: Can't find this part

Post by 95ninety » Sat Feb 02, 2019 3:01 pm

I had these codes along with a few others when my fan was running at all times. I replaced the coolant temp sensor and all of them went away. Might be something to look at after you diagnose your module and fan to be in good working order.

Classik
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Re: Can't find this part

Post by Classik » Sat Feb 02, 2019 4:39 pm

Thanks all for the comments and suggestions. As a matter of facts I've changed the coolant temperature sensor last week, part of a preventive maintenance campaign along with the N249 valve and a few other bits. But no change on the faut codes, as expected in my case..
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Re: Can't find this part

Post by Classik » Fri Feb 08, 2019 7:22 am

MattV8 wrote:
Sat Feb 02, 2019 11:15 am
Definately R8 Coils.
Really?
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Shoppinit
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Re: Can't find this part

Post by Shoppinit » Fri Feb 08, 2019 8:42 am

^Joke for the initiated. If you look back far enough you'll get it.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Can't find this part

Post by Classik » Fri Feb 08, 2019 1:25 pm

Ha, at least I didn't jump on it saying it must be a great upgrade ;)
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Re: Can't find this part

Post by Shoppinit » Fri Feb 08, 2019 1:46 pm

You should definitely get the R8 coolant cap though.
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

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Re: Can't find this part

Post by Classik » Fri Feb 08, 2019 3:00 pm

Yeah, just started saving for that one! :thumbs:
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Re: Can't find this part

Post by Shoppinit » Fri Feb 08, 2019 3:08 pm

You figure out where your problem is? Did you do the output tests with the Vagcom?
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

Classik
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Re: Can't find this part

Post by Classik » Sat Feb 09, 2019 12:32 am

Unfortunately no, didn't find a minute to do the tests yet. Hopefully this should be done over the weekend, and I'll report of course. Thanks again for the follow up.
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Re: Can't find this part

Post by Classik » Mon Feb 11, 2019 5:53 pm

Right, so I did the output tests and both fans can be activated fine using the Vagcom. I suppose it simply means my second-hand fan ECU is also faulty? Shout...
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Re: Can't find this part

Post by Shoppinit » Mon Feb 11, 2019 7:16 pm

With the engine stone cold, if you clear the fault codes then run the fan with the Vagcom does the fault code appear immediately?

If not, then do the same test when the car has just been driven and everything is hot.

If it faults only when hot, then could be a bad solder joint on the PCB. Or possibly water ingress damage.

Or it could be bad wiring / electrical connections. Most likely at or near the connector. How do the contacts look?

If you tap the unit when it's running the fan with a screwdriver or something, does it fault out?

You could always open the old module and try reflowing everything if you've got the gear and the know-how. I fixed a friend's S8 ECU this way (that was water ingress damage). No-one was more surprised than me. :)
Daytona RS6 C5 Avant. Viper'd, Billies, Waggers, MTM box brain, C6 stoppers, xcarlink, R8 coolant cap (woohoo)
///M3 E46 | XC90 (V8, natch) | Passat GTE | RR Classic V8 flapper
"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair."

Classik
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Re: Can't find this part

Post by Classik » Mon Feb 11, 2019 7:44 pm

Hi Shopp,

With the engine cold, I can indeed clear the codes and they come back only when the car has been driven. Looks like it doesn't take long for the codes to come back but I'll try to investigate what triggers them as suggested above. Good suggestions also regarding the option to repair the old ECU, I'll give it a try: may be an faulty transistor or voltage regulator, which I could manage. Never dared to try that, but with a bit of luck it may be something obvious. Many thanks again, I'll keep you guys posted of course.
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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MeTsU
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Re: Can't find this part

Post by MeTsU » Tue Feb 12, 2019 6:20 am

Classik wrote:
Mon Feb 11, 2019 5:53 pm
Right, so I did the output tests and both fans can be activated fine using the Vagcom. I suppose it simply means my second-hand fan ECU is also faulty? Shout...
Would you mind adding the steps followed in VCDS to perform the output tests? Might be good for someone who stumbles across this thread in the future. :beerchug:
2004 Audi RS6 Avant Plus #283

Classik
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Re: Can't find this part

Post by Classik » Tue Feb 12, 2019 7:05 am

Sure MeTsu, actually it's quite straightforward and well documented on the VCDS Rosstech website (Google "VCDS output tests").
Select the engine ECU, click on the output test button.
Then just start the output tests sequence. Activation of the secondary and primary fans is one of them. Don't wait too long, the fans won't spin forever. If you're lucky enough your VCDS version can allow direct access to each specific test (not my case).
Does that help?
Best
RS6 C5 Avant 2003 Daytona Grey
Loba 650 turbos - Wagner IC - 200 cells cats - Milltek cat-back - Hotchkis bars - Bilstein B16 - MTM Wheels - oem coolant cap

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Re: Can't find this part

Post by MeTsU » Tue Feb 12, 2019 7:28 am

Classik wrote:
Tue Feb 12, 2019 7:05 am
Sure MeTsu, actually it's quite straightforward and well documented on the VCDS Rosstech website (Google "VCDS output tests").
Select the engine ECU, click on the output test button.
Then just start the output tests sequence. Activation of the secondary and primary fans is one of them. Don't wait too long, the fans won't spin forever. If you're lucky enough your VCDS version can allow direct access to each specific test (not my case).
Does that help?
Best
Thanks Classik, all good, just thought if someone popped into the thread and didn't know.
2004 Audi RS6 Avant Plus #283

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