So I've only had my Superb less than a month and had pencilled in this week to have a look under the battery to see how the water situation was...

It's bad.

I've just done a 500 mile round trip in the Superb through a lot of very, very wet Welsh weather and in the last 48 hours the dreaded symptoms started to appear: courtesy light would not work, then the footwell lights didn't work, and by the time I arrived home last night the main reading light didn't work.

So I had the battery out today (makes it sound so simple!) and lo and behold there was nearly 2 inches of water in the plenum chamber. I've cleared it now but there was a leak into the pollen filter too and on lifting the carpet in the passenger footwell the underlay is dripping wet through. There's a bit of black mould on the underlay and some of the wires leading into the CCU are covered in copper sulphate which explains everything.

My question now is this:

1) There were 3 yellow/green wires that had corroded inside a node. I've stripped them back to new wire and soldered them together but that's as far as I managed today. There's about 5/6 red and black wires inside another node next to the CCU that look completely rotten - anyone know what they are for?

2) Can anyone point me to an online Passat/Superb wiring diagram? There's zillions of wires to check inside the loom but not sure which control the internal lighting that I'm having issues with. I don't have a Haynes manual (have ordered one but won't be here until next week).

3) What's the best way of joining wires together? I'm cutting back to good wire and soldering them but are there any easier techniques that anyone recommends?

Cheers for any help!

Edited 24 February, 201115 yr by BDZ10

your right about the number of wires and in the past I tried to decipher an old loom but I gave up it was like a maize A few tips for you remove the passenger seat (you dont have to disconnect the wires just push it over carefully out of the way) then lift the carpet front and rear as there is a large bunch of wires connected in the rear and it is these that control the inside lights and puddle lights just redo the lot. another thing remove the kick panel on the passenger side and dry this out well as in there there is a load of plugs in there and these will eventually give you grief particularly the big grey one - this controls the bonnet open symbol on the dash and also resets the oil low warning symbol so I would unplug this one and dry it well with the hairdryer - soldering (the little gas one that you put lighter gas into is a great piece of kit) does seem to be the best method of reconnecting the wires using heat shrink to insulate the joints I am not a great believer in the crimped joints unlike Mr Skoda There are loads of threads on this problem throughout this site and I think it,s like a rite of passage to being a suberb owner you must lift the passenger carpet and burn out the wife's hairdryer to become a member of the gang

Edited 25 February, 201115 yr by dohertyjj

Am happy to say that I've finally finished and the fault is now fixed!

The corrosion wasn't as bad as some people seem to have experienced but all the nodes nearest the CCU were soaked and dissolved/covered in green slime so I've replaced them all, dried out the whole underlay and now all the interior lights, puddle lights, glovebox lights etc work perfectly. Has cost me about £35 to fix (mostly spent on tools I didn't own before) and taken about 6 hours, though most of that was figuring out how to take the trim off and carpets up, it would be a lot quicker next time.

Only want to add how shocked I am at the design fault that leads to this problem. I've had a few VAG cars and my dad won't drive anything but VWs and they've always been utterly reliable but this electrical fault seems so obvious it's almost like someone did it on purpose! I can't believe a company like VAG would make it so easy for water to get in, join the electrics so cheaply and bind them together with a water-retaining material, and then place the most important electrical components right at the lowest point in the car where all the water gathers. Unbelievable.

As a word of encouragement to anyone else with this problem, don't be afraid to give it a go. I've never done much work on cars beyond very basic servicing (oil, plugs, drive belt etc) but this wasn't really that hard as long as you have time. If you can assemble an IKEA cupboard you can take apart and re-assemble the trim to fix this problem and soldering and resealing the joints is quite easy once you get the hang of it.

After having said all that, this shouldn't distract from the fact that despite this horrendous design fault, the Superb is a brilliant, brillant car.

Hi BDZ10. I am having exactly same situation with my Superb. I have cleaned the drain hole under the battery, so there is no more water in the plenum chamber, but my rear footwell still seems to be getting water from somewhere (lifted up the carpet, wiped the metal floor underneath dry and after few hours of rainfall there were about 50ml of water in it again). Any ideas?

Sunroof drains blocked?

Hi BDZ10. I am having exactly same situation with my Superb. I have cleaned the drain hole under the battery, so there is no more water in the plenum chamber, but my rear footwell still seems to be getting water from somewhere (lifted up the carpet, wiped the metal floor underneath dry and after few hours of rainfall there were about 50ml of water in it again). Any ideas?

Did you completely dry out all the carpet and underlay? The underlay is superb at holding water and it takes ages to dry out so even if you've wiped out the moisture it will reappear even if the carpet is bone dry. Fortunately I only had quite a small wet area but it must have taken about 2-3 hours with the hairdryer to get it dry.

Also worth checking there's no sludge sitting up against the pollen filter housing (this was happening on mine) and that the filter housing has been waterproofed.

No luxury of sunrooof in my Superb... Will try to follow Gizmo68's post tomorrow to seal the pollen filter housing : http://briskoda.net/forums/blog/18/entry-62-superb-mki-water-ingress-cure/. And will also dry the carpet and underlay as much as I can....Will post the result tomorrow.

Afternoon. To start with I was trying to do things properly and went to Skoda and VW dealers to try and get a new seal for the pollen filter. But as I was expecting I had to order it and I could only get as the parts guy at WV said "about 20 meters of it for 30 odd quid"...They also said they could reseal the pollen filter for me, and the cost was just under £200. So, I've chosen a silicone solution. Removed to pollen filter housing and indeed the seal was in a very poor condition. Here's what it looked like:

Filled it with silicone and put everything back together.

Then I decided to look under the passenger side carpet and the water situation there was really bad. So, after removing the seat I've managed to cut the carpet underlay out, which is now drying on my garden fence....

The CCU wasn't flooded but the floow underneath it was quite damp...

Will put everything back tomorrow and hopefully this will be the end of the water ingress problem with my Superb.

Edited 26 February, 201115 yr by Naz_G

Good effort Naz. How wet was the underlay? Were all the electrics ok i.e. not corroded?

The underlay was properly soaking. When I lifted the carpet there was about 0.5 to 1 liter of water on the floor itself. The cabling was just wet, but without signs of corrosion. I made it dry by using a very professional tool: wife's hairdryer. The driver's side carpet and underlay were quite wet as well, but I decided not to remove it as there are no important components underneath. I just used a little electric heater there for about 1.5 hrs and it seems dry now.

It is unbelivable how a company like VAG could do such a silly engineering mistake. I had a 2002 Passat before and the plenum chamber once filled with 3-4 inches of water. It didn't go inside though. I cleared the drain hole under the battery and the water was gone. About 3 month after that I had a recall letter from VW asking me to bring my passat in, so they could check plenum chamber drain holes blockage (nothing about the pollen filter housing though). I went there, they took a car into the workshop for about 1 hour, and then just told me that it was ok. Of course, it was, I cleared it myself...

Edited 26 February, 201115 yr by Naz_G

And a further update. Redone a pollen filter seal with a proper silicone, and the passenger side never got wet again. But, after it rained quite intensively last Sunday, I checked the driver's side floor and OMG it is wet again. Had enough of this sh....t now. Found a post on a web about the seal on the other side of the plenum chamber, under the ECU. Here is the link: http://www.passatworld.com/forums/showpost.php?p=2453843&postcount=28. Just wondering whether anyone has ever done this before and how did it go. Will disconect the battery of course, but not sure if this will make the ECU removal 100% safe.

The problem here is the very poor conversion of the B5.5 to right hand drive. LHD B5.5s don't suffer nearly as much unless you have a lot of bio crud in the plenum box.

Because relatively few RHD B5.5s were produced, VAG decided to do nothing about the problem and even re-introduced it to the Superb. Nice people.

The seal under the ECU box is similar to the pollen filter housing outer seal (ie. useless) but the drainage angles are more favourable here and most RHD cars don't leak at this point unless parked steeply nose up. Check first the grommet for the bonnet release cable. In a further masterstroke of design, it lives in a recess so that the scuttle pressing acts as a rainwater funnel...

When some dealers pull the front to change the belts, they don't bother to disconnect the bonnet release cable - there's a coupler in it for this purpose. Instead, the monkeys just yank on it, breaking the bellows type grommet. You know what happens next.

rotodiesel.

So I've only had my Superb less than a month and had pencilled in this week to have a look under the battery to see how the water situation was...

It's bad.

I've just done a 500 mile round trip in the Superb through a lot of very, very wet Welsh weather and in the last 48 hours the dreaded symptoms started to appear: courtesy light would not work, then the footwell lights didn't work, and by the time I arrived home last night the main reading light didn't work.

So I had the battery out today (makes it sound so simple!) and lo and behold there was nearly 2 inches of water in the plenum chamber. I've cleared it now but there was a leak into the pollen filter too and on lifting the carpet in the passenger footwell the underlay is dripping wet through. There's a bit of black mould on the underlay and some of the wires leading into the CCU are covered in copper sulphate which explains everything.

My question now is this:

1) There were 3 yellow/green wires that had corroded inside a node. I've stripped them back to new wire and soldered them together but that's as far as I managed today. There's about 5/6 red and black wires inside another node next to the CCU that look completely rotten - anyone know what they are for?

2) Can anyone point me to an online Passat/Superb wiring diagram? There's zillions of wires to check inside the loom but not sure which control the internal lighting that I'm having issues with. I don't have a Haynes manual (have ordered one but won't be here until next week).

3) What's the best way of joining wires together? I'm cutting back to good wire and soldering them but are there any easier techniques that anyone recommends?

Cheers for any help!

hi there i have the exact problem, check my report and pictures. its superb wiring nodes, page 2 i think.

the rear wiring was totally knacked.

but i didnt know the drivers side could flood also, removal of the ecu under the bonnet will be the order of the day and re seal

I am desperately trying to find someone to help sort this out on mine too.

No interior lights and drivers door lock motor gone

In Nottingham/Derby area but willing to travel to get it sorted

Cash paid.

You must have an indy VAG specialist somewhere around there?

DSB Autocare in Nottingham always get a good writeup - no first hand experience.

rotodiesel.

DSB Autocare in Nottingham always get a good writeup - no first hand experience.

rotodiesel.

OK mate thanks, will give them a bell tomrw

)

The problem here is the very poor conversion of the B5.5 to right hand drive. LHD B5.5s don't suffer nearly as much unless you have a lot of bio crud in the plenum box.

Because relatively few RHD B5.5s were produced, VAG decided to do nothing about the problem and even re-introduced it to the Superb. Nice people.

The seal under the ECU box is similar to the pollen filter housing outer seal (ie. useless) but the drainage angles are more favourable here and most RHD cars don't leak at this point unless parked steeply nose up. Check first the grommet for the bonnet release cable. In a further masterstroke of design, it lives in a recess so that the scuttle pressing acts as a rainwater funnel...

When some dealers pull the front to change the belts, they don't bother to disconnect the bonnet release cable - there's a coupler in it for this purpose. Instead, the monkeys just yank on it, breaking the bellows type grommet. You know what happens next.

rotodiesel.

Had a quick look at the bonnet release cable gromnet. Looks intact at the first sight. The plan for Saturday is to take take it out and look whether there are signs od water going into the car through it. Also, after hosing the windscreen on the driver's side I have noticed that quite a lot of water is flowing under the ECU box and then comes out on the other side of it, I just have a feeling that this might be getting in through there as well. So, will disconnect the ECU and just check/reseal if needed. As far as I understand disconnecting the battery will keep my ECU settings safe. Will post the update then.

Spoke to a very friendly chap at DSB and the car is now booked in to be sorted next friday, £50 quoted