Wet carpet behind passenger seat

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hawky443

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Dec 1, 2025
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I've been noticing the car steaming up a lot even when not being driven, I checked the carpets and found that behind the passenger seat floor (left side UK) the carpet is damp. I've also noticed condensation in the boot, now I did leave the boot open one day like a proper tool when It was raining. Is there a common place that causes these issues? I was thinking the soft top seal at the back but I'm not sure if that would cause these issues or something else?

Any advice is appreciated 👍
 
There are drains built into the sides of the roof with the soft top that may be deteriorated.
You will need to check those hoses and collection systems, most likely that's where the water is coming from.
 
The floor covering is very thick. Around 2inches of foam under the carpet. It can hold a LOT of water before you even feel the wetness. So the front is likely soaking as well.

I think water can leak in at the front and make it's way to the back if the car is parked facing slightly uphill so, in my.mind, just because water is under the seats.doesn't exclude leaks at the other common places.
 
Hello mate

I got my Z3 a couple of months ago and I didn't realise it at first but the carpet was absolutely soaked through, mainly on the drivers side but the passenger side was wet too. I had to reluctantly remove the carpets completely to work out where it was coming from.

It turned out to be coming in through a gap in the butyl sealant, along the sealing frame.

Another common one is a leaky door seal/vapour barrier (really easy to do yourself with some butyl tape).

I'd maybe do some water tests on it, pour some over the outside and see if you can spot any drips or runs on the inside.

Re steamy boot - Have you checked under the battery for water, and down under that little plastic cubby hole on the right, in the boot to make sure there's no water sitting in there?
 
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hawky443 said:
I've been noticing the car steaming up a lot even when not being driven, I checked the carpets and found that behind the passenger seat floor (left side UK) the carpet is damp. I've also noticed condensation in the boot, now I did leave the boot open one day like a proper tool when It was raining. Is there a common place that causes these issues? I was thinking the soft top seal at the back but I'm not sure if that would cause these issues or something else?

Any advice is appreciated 👍
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The boot, or trunk as some call it, could also be the antenna grommet, or the 3rd brake light seal, you may have two sources of leaks
 
hawky443 said:
I've been noticing the car steaming up a lot even when not being driven, I checked the carpets and found that behind the passenger seat floor (left side UK) the carpet is damp. I've also noticed condensation in the boot, now I did leave the boot open one day like a proper tool when It was raining. Is there a common place that causes these issues? I was thinking the soft top seal at the back but I'm not sure if that would cause these issues or something else?

Any advice is appreciated 👍
Click to expand...
Sounds like a water ingress issue somewhere. Common spots are door seals, rear light seals, boot seal, or blocked drain holes, especially if you’ve had the boot open in the rain. A rear soft-top seal could also let water track forward. Best bet is to dry it out and then hose one area at a time to pinpoint the leak.
 
Unfortunately being in Scotland and it being December it's always wet, need to wait for a few dry days 😂
 
hawky443 said:
Just went in to check, battery box is full of water... Help! 😭
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You did say you'd left the boot open one day while it was raining. That wouldn't help.

But things in the boot to look for are, as was already meantioned, seals around the lights. If there's water in the rear left corner of the boot then that would likely be the aeriel grommet. Also check the seal around brake light in the bootlid.
 
There should be a rubber cap at the bottom of the battery, pull it so you can drain the compartment.
While you are at it, the carpet in the passenger compartment needs to be drained as well. These things need attention right away to prevent the formation of rust.
 
Rudyrov said:
There should be a rubber cap at the bottom of the battery, pull it so you can drain the compartment.
While you are at it, the carpet in the passenger compartment needs to be drained as well. These things need attention right away to prevent the formation of rust.
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Agreed, pull the carpets out asap.
 
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