An interesting journey home.....

4.2 V8 40v biturbo - 450 bhp
4.2 V8 40v biturbo - 480 bhp (plus)
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lala
2nd Gear
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Joined: Mon Jun 11, 2012 8:49 pm
Location: Colchester, Essex

An interesting journey home.....

Post by lala » Fri Sep 25, 2015 10:41 am

Ok, so I've not had any reoccurrence of the p0491 and p0492 codes which is good...
but I've had a few other problems......
Please no flaming me, I'm very emotional at the moment :roll:
So after an very heavy night out, my wife drove the car for me to fuel up for our return journey, went to a Shell garage for the Optimax and this is where it all went wrong! I saw the Optimax pump and said to fill up at that pump. I got out and started filling the car but not very successfully, 2 litres later and I realised why....Optimax in Spain is also diesel :knob: All I saw was the Optimax sign. I changed pumps,filled up with 98ron and ended up with a full tank approx 80 litres of 98ron and 2 litres of diesel, the tank was approx 50% when this happened.
The car started and ran fine, drove it from Spain to France, about 850kms and filled back up every half tank, no problems.
Stayed overnight in France and then drove from France back to Colchester, about 1200kms and this is where the problems started. On the autoroute, doing 130km/h, the car suddenly lost power and the EPC and ESP lights came on. Pulled over, the engine was hunting slightly, turned off and the restarted a few minutes later, lights stayed on but car ran fine. Used ultraguage to clear the fault, which it reported as being p0606.
A few hundred kms or so and it happened again, this time i was flooring it up a very steep hill, total loss of power and nowhere escape, without thinking, I switched the ignition off and on, whilst still in gear and doing 130km/h and the car restarted with no error codes and has driven faultlessly since!!!
I have no idea of whats going on. Apart from obviously been a bit stupid with the fuel, anyone have an idea of what could be wrong?
On the plus side, I made it all the way home this time :rocker:
2004 RS6 C5 Avant

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Nobby
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Re: An interesting journey home.....

Post by Nobby » Fri Sep 25, 2015 11:23 am

Having Googled it, it looks like P0606 errors are relating to the ECU. Might be worth checking for water ingress/dodgy connectors.
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lala
2nd Gear
Posts: 107
Joined: Mon Jun 11, 2012 8:49 pm
Location: Colchester, Essex

Re: An interesting journey home.....

Post by lala » Fri Sep 25, 2015 11:53 am

I googled as well, I'm going to check the car out but is it usual for the symptoms to come and go if the ecu is on its way out?
2004 RS6 C5 Avant

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Shoppinit
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Re: An interesting journey home.....

Post by Shoppinit » Fri Sep 25, 2015 11:57 am

Yeah, I think the bad fuel is a red herring. You might have shortened the life of your cats, but I can't see it causing any other issues in such diluted form.

Confirm what Nobby said. It's a bad ECU error code. Pretty abrupt description and solution. Borked ECU, replace ECU...

Must have detected an internal fault. Start searching on ebay...
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