I all i have bern having maf problems lately fault code 17552 and when checking wires from maf towards bulkhead i put my hand ontop of black box on battery (without cover) and it was hot then when i had a closer lokk this is what i found 

Any help on what this cable is for? and what would cause this to melt ? Also can i get just the fuse think it's a 100amp fuse or do i have to buy the whole thing thanks for any info

Very common problem for these fuse boxes to get hot and melty. When mine did it, all the dashboard electrics started to cut in and out. Easiest was just to replace the whole box. I got one from a scrap yard for a tenner.

There's a couple on ebay

 

https://www.ebay.co.uk/itm/1998-2005-SKODA-AUDI-A3-VW-GOLF-MK4-SEAT-LEON-DIESEL-FUSEBOX-1J0937550AC/202018216526?fits=Model%3AOctavia|Cars+Type%3ARS+1.8+T&epid=2233305417&hash=item2f09395a4e:g:K6QAAOSwJ7RYTp97

 

Or try giving Devonutopia a message on here, he breaks Octavias quite regularly so may have a couple knocking around.

Cheers do you know what this wire is for ? And would it have anything to do with the 17552 fault code thanks

I believe that the black wire in question goes to the alternator. Depending on how corroded the connection is, it may also be worth replacing that cable to. I shouldn't have thought it'll be related to the MAF code that's being thrown up.

Cheers for the help