Hello, I had the heater matrix replaced on my 2017 Mk 3.5 Octavia estate at the back end of last year. There had been a month or so of coolant leaking and the heater matrix replacement has fixed the issue. When I’ve gone to clean my car last month, the amount that had actually leaked became apparent and when I lifted the rubber floor mats on the passenger front and rear footwells to vacuum, the carpet and underfelt was soaking. Whilst the carpet is now much drier, I have had a car detailer look at it today to see how they would recommend cleaning. The car detailer said he had seen and repaired this type of issue before, and recommended to get a new underfelt. He demonstrated that the old one was starting to turn to mush and couldn’t really be rescued. I am not very DIY minded when it comes to cars (I can change a tyre and top up liquids!) but the detailer has said he will remove the passenger seat, sills and fit a new underlay for me, before doing a carpet wash and general valet. I just need to find an underfelt (can be second hand). Does anybody have experience of this, and know where I could get underfelt from for this model? Appreciate I will probably have to buy a full underlay and cut to just use passenger side. I am UK based. Thank you.

Came across this company when looking for carpet. They do underlay 1.5m wide per metre. Another option would be scrapyard.

https://www.carcarpets.co.uk/

Alasdair

What he said. You can also get it from Skoda but that will probably cost you an arm and a leg.

Speaking from experience (as both a detailer and someone that's had water ingress issues) this detailer seems like a great guy. There are a few things I'd suggest also doing. Firstly, I'd get a couple of those reuseable dehumidifier bags. I keep three or so dotted around my car and it keeps moisture at bay. You'll want to do this to avoid any mould/damp issues (coolant aside, I presume you'll have used water to top it up). Secondly, I would ask the detailer if he could, pretty please, lift the carpets one morning and then come back the following day. You'll have to pay him a bit more, but it would be very good for everything to air out. At this point, I'd also get some APC or IPA on a cloth and just wipe down what you can.

These steps are probably overkill, and feel free to ignore them - but, from my experience, once you get mould or damp in a car, that's pretty much it. You don't want that to happen here!

4 minutes ago, OccyVRS said:

once you get mould or damp in a car, that's pretty much it

I agree left my old Seat altea over winter and when I opened it early on this year it was covered in grey green mold. Its off the road and is a work car so wiped everything down/hoovered and then sprayed with diluted vinegar. Left in sun to dry out with all windows down and so far so good. Still smells a bit like a chip shop but smell is getting better and the mold has gone.

Alasdair

Thanks all for your advice and suggestions, much appreciated.

I’m struggling to find online a 2nd hand replacement for the underlay, which would have been my preference. There is a mk2 underlay currently for sale on eBay but not sure how different that would be to the mk3?

It may be that I just buy a couple of metres of new generic underlay as @Alasdair1 has suggested and cut to fit underneath the passenger side carpet.