I have a Skoda Fabia TSI Elegance Estate 2013. I have rust & mould where the spare tyre is and rust under rear seats. Is the water coming in through the rear door seals..?

There are flaps behind the rear lights to stop water from getting in. This is the usual source of leaks at the back end. You must remove the rear bumper and the rear lights to get at them. There is a lot about the problem here.

The flaps are to let air / pressure out, they can allow water in.

As can the rear light seals. 

 

Lots of threads in this section if you do a word search.

 

 

Edited 23 August, 20241 yr by Ootohere