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This is a second post about an A6 Avant 2006 4F 3.2 FSI, the first post can be found here;

I have the VCDS software, please take account of that when reading.

Travelling home on the M1 in NSW with cruise engaged, the car suddenly dumped the cruise and went into Limp Mode. EPC lit up on the dash.
As entertaining as that was, working over from the outside lane to the inside lane in fairly heavy traffic with no power, it heralded the start of some major issues.
Safely over in the inside lane, I was able to turn the ignition off, wait a couple of seconds and then turn it back on. I was going quickly enough for the auto box to 'jump start' the engine. Phew.
Fault gone, power back, drama over, home with no further issues.

From then on other faults started to appear. I scanned with VCDS, found all sorts of issues, cleared the codes, all good.
This continued, with a steady downward trend, eventually multiple faults that wouldn't clear. Some are listed below
  • ABS controller - DTC memory
  • Auto Gearbox - Throttle Position Sensor
  • Engine - Throttle Position Sensor, DTC Memory ABS
  • Handbrake - Auto release issue, DTC Memory
Throttle Position Sensor (G79) had come up as being the cause of the EPC warning and the Limp Mode.

It was the Handbrake issue that finally made me realise that all these problems were simply because these control units need to know where the throttle is. How can the auto release work if it does not know that you have pressed the throttle to set off again!
Yeah, looking back it was pretty obvious what the root cause was, but at the time with so many modules going belly up, or so it seemed, it was a bit like, "couldn't see the wood for the trees".

After much searching for answers with no success, I decided to pull the throttle unit out and see if anything was wrong and could possibly be fixed.
Was a bit of fun getting the lower dash out with no knowledge of where the fixings were located, but once that was out it was easy to unplug the unit and remove it.
The throttle unit case was easy to open, but once inside, oh dear. Solid state, PCB tucked away in the main body and just the (possible) coil unit attached to the pedal.

All I could do was hose things out with switch cleaner, including the socket and plug contacts and reassemble.
Scanned for the umpteenth time, cleared codes and rescanned. Nothing, no warnings, dashboard clear

It was about that time that I fully expected to wake up from this wonderful dream, but no, it was true.

In summary, what appears to be multiple very expensive problems, can be simply down to one or two poor electrical contacts.
I hope this may help someone avoid replacing parts, or solve a problem, maybe both.
 
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