Andymod

Load detection fault is normally caused by a broken wire in a 2 pin connector block down in front of the gearbox. It's best accessed from underneath.

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Can also be casting sand, which was not fully cleaned off in manufacturing

Volkswagen group don't advise any additives although they do actually have genuine additives. Might be worth trying an additive or wait till you need to refuel and try super unleaded.

Might be worth filling the tank with super unleaded and see if it stops the noise.

Is it a metallic rattle?. What fuel do you use just thinking it may be pinking/detonation.