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All in all it went well and Im so glad to have my 2000 D2 A8 running like a champ again. The transmission was in superb condition just as foreseen -- EH
Tech Article

Audi D2 A8 Secondary Air Injection Fuse Holder

Last Updated: 02/17/2017
Parts Group: Fuse holder
This article discusses the fuse holder for the 40 amp fuse in the relay box in the passenger footwell of a D2 Audi A8 (1997 through 2002) with the main focus being on a meltdown whose aftermath we saw. If you're not here for the technical analysis but would rather buy a used unit from us, guaranteed to work and fit, then please select the link below.The information herein is based on my Audi A8 D2 Quattro project car, a 1998 model.

We were chasing an electrical problem that involved removing the wooden cover above the relay box in the passenger footwell area. We noticed with concern that the compressed wood shows signs of water damage, and then the news got worse: the fuse holder for the 40 amp fuse had melted dramatically:

Inherently a fuse is supposed to prevent exactly that sort of thing from happening, but if there is a short circuit across the base of the fuse holder, this can happen. However, a fuse holder is designed specifically to avoid such a short circuit.

Even so, had water leaked into that area, it would explain what we saw, since water is a conductor. The heat from the meltdown was so severe that it had also damaged the plastic cover a nearby relay.

We decided to cut the wiring and splice in a healthy unit from a donor car.

With such heavy current involved, we are making extra sure that nothing comes apart, so we are using with heat-shrink tubing and we plan to solder the connections.

We suspect that this is the 40 amp fuse for the secondary air injection. If it is, it might explain why, on our car, this function has never worked.
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