Quote Originally Posted by Wudka View Post
Update.

Seems this was spot on. I started going plug for plug this morning, checking each sensor and connector and this connector was the first that I have found with moisture/corrosion.

I have cleaned it the best that I can and need to figure out how to do a better job of the clean. I have bought contact cleaner and will try and blow it through, grease it up and reassemble.
Might take my dads advice and try and seal up the top the plug too, although access is not great.

Following the initial clean, which was basic for lack of a compressor and tools to get in there, the car is now driving without fault.

I think this should be a prohibitive maintenance check in the schedule. Ridiculous that Audi dont communicate this design fault to customers and fix it.

I want to upload photos for others reference, but for some reason it is not letting me.

Further update,

The gearbox coolant solenoid valve is very much so the culprit here, with the plug to this valve also corroded and wet. As nominated in other threads with this issue, the coolant escapes this valve, follows the cabling down via the loom to the gearbox control module plug and then corrodes that away to the point of a multi thousand dollar repair if you do not get sufficient intermittent issues and investigate in time - In hindsight, my car had shown signs a few months back, nominating gearbox cooling issues, but the message disappeared almost immediately and I didn't think to investigate the wiring, instead looking into finding a good price to change the gearbox oil.

I have spent the weekend looking into this and am confident that Audi know about with what I have been able to uncover, yet they choose to do nothing about it.

I would strongly urge all A6 owners to at least investigate the condition of their solenoid valves and check the gearbox control module plug for signs of moisture. If none, then modify the harness to allow water to drip away(Cut the heat sleeves) and cut a drain hole into the bottom of the gearbox control module plug cover.

This might save you thousands in repairs and could potentially save you from a major accident, for if it fails immediately like mine did, then you might get Tboned etc.

Thank you for helping me!