996 Cabrio wont start after leak

Hello everyone. I've got a 996 Cabrio 02 (RHD - Im in the UK) and a leak flooded the rear passenger seat and footwell (I took out over half a bucket of water). First symptoms were the alarm going off for no reason. The strange thing is that I took it out for a 15 min drive with the heater on full and windows down to help dry it out. I parked the car and the next day it wouldn't start. I peeled back the rear carpets and the sponge underneath was still soaking so I've been trying to dry it out with a hair dryer for a few days. Its (carpet/sponge) almost totally dry apart from some edges but it still wont start. In the meantime I've also changed the battery as it was only showing about 10 volts. Also tried to jump start it using the terminals in the engine bay but still wont start. I dont think its an alarm issue as that seems to work fine when I test it - leaving windows open and engage alarm then put my hand in car causes the alarm to sound. The central locking works correctly too as do all the other features; PCM (radio), dashboard lights all seem to work. Any ideas would be welcome.

In the US some of the electric control units for the car are under the drivers seat. Not sure which side hey are on in thevUK with RHD. However it is a known issue with the drain for he cab top being plugged and causing the under seat area to flood and damage the electronics. These can be very expensive to replace and require reprogramming by a dealer. If yours have gotten wet then the best thing to do is not to drive the car, but to take out they control module and dry it out before it is subject to current. This may not be possible now, but it is worth a try. Look for any corrosion on the connectors, etc. If you do searches here you will find lots of posts on this problem and how to clean the drains sort does not happen again.

Hey Doug thanks for the tip. The strange thing is that none of the electronic boxes under the passenger seat got wet; only under the rear seats and rear footwell behind the passenger side. The car wont start so I cant drive it anyway but I'll try and dig up the posts on cleaning the drains and see how it goes.

As Doug says. Where the alarm control modual for the car is laying is at the lowest part of the car. Under the drivers seat, in a depression in the floor. Above that is another box which is attached to the bottom of the seat which control the seats movement. If the alarm control gets wet the alarm probably would go off as yours did. I have a C2 99 Cab same as yours but LHD. Mine is the 535 alarm modual. The cost of another on ebay is $444 but you can bet your **** you wont get one as cheap as that from Porche plus you pay for labour. Check to see if your car Insurance covers flooding. If so you are in with a chance. You may think under the drivers seat was not flooded but thats the lowest part fo the car and water gets places you wouldn't believe possible. If your insurcance covers flooding then my advice is for you to flat bed it to a Porsche place and get them to change it. You could change it yourself but would have to have it set up at Porsche who have the PST2 or PIWIS testers to set these cars up. Anyway good luck with your venture. How did the inside get wet anyway if you dont mind me asking?

Thanks for that info... Car got flooded probably due to blocked drains. I think its the ones at the back which drain the water that gets between the rear wings and the hood cover. I say I think that because to test it I put some (masking) tape over the space described and the leak seems to have stopped or at least I cant see any more water collecting under the carpets in the rear foot well. Wait it gets a bit strange now... I had an auto electrician come and see the car and he plugged in his laptop and said that there were no errors coming back from the engine and he assessed that its not the alarm or immobilizer modules as that would show as an error on his laptop. He then contorted himself to fit under the steering wheel and fiddled around with the switch under the clutch. He tried the car again and lo and behold it started! Yay! He turned it off and then removed the switch completely and then turned it over and it started again. So he turned it off again and then refitted the switch again and it started again! He turned it off again and then he left it on for about 15 minutes and then off again and then tried it again and it wouldn't start!. So he called a Porsche indy place and the guy told him it was probably the ignition switch. So I ordered the �15 part off the web and I installed it myself but that did not work either. So OK, were making progress or at least eliminating things. I don't believe its the alarm module as I've tested it and it seems OK. I opened the windows and armed/locked the car using the key. I waited for the alarms light to stabalize then waived my hand about inside the car and it set the alarm off. The alarm stopped when I disarmed the alarm from the key again. If the alarm module wasn't working the alarm shouldn't go off, right? So, today i had another stab at it and while I had the heater ducts under the dash out (to change the ignition switch) I had a play about with the clutch switch too. Took it out cleaned the contacts inside and put it back and tried quite a few times but still wont start. I'm starting to think that maybe there's an intermittent fault on the starter motor. But I'm also thinking that maybe theres an intermittent fault on the clutch switch too. However, the auto electrician called a Porsche specialist and they told him its not that the clutch switch as it wouldn't stop the car from starting. Anyway I'm going to bite the bullet and call the AA to take it to a Porsche indy (not ops). Hopefully it wont cost me an arm and a leg! Will post back and let you know the outcome. Unless anyone has anymore ideas???

You may want to replace the clutch switch by a jumper cable so the clutch switch is out of the picture and see what you get. Just make sure you are in neutral when starting car since it will start even the clutch is not depressed. Oh yea, the clutch switch will stop the starter from running since that's its sole purpose.

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Oh! I was told that the clutch switch is not for starting the car but is used "downstream" for giving info to the ecu (engine management). That makes sense to me as I have had the car for 5 or so months and have never needed to depress the clutch to start the engine! But as its an inexpensive item I've just ordered a new clutch switch and will see where that takes me.

I still say alarm module.

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But the alarm works. I've tested it. In fact all the electronics appear to be OK. All the dash lights work as do all the other systems. Except it wont fire up. And the auto electrician said that if the alarm module or immobilizer had faults they would show up on his laptop as errors. Or was he talking cr@p?

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Now I see you're in UK so maybe that's the difference? I'm suer in US, we need to depress the clutch to crank the engine. Now I remember though, the clutch switch (in US at least) is used to retard the engine timing as well when the clutch is depressed. This helps smooth out the gear change. Kinda like a clutch delay valve some other cars have. So yea, if cars in UK don't use the clutch switch like in US, then probably it's not the clutch switch.

OK... Its taken a while to get my car back on the road as I wanted to be absolutely sure that it was fully dry before I took it in to an indy Porsche specialist. Got the car back today...10/10 to those that called it right, it was after all the Alarm module. Apparently the mechanic took the alarm module out and cleaned it (it had some green stuff inside - which I assume was mould of some kind) and the car started. But afterwards it wouldn't again so it was best to change it. As if that wasn't bad enough he said that I needed new key heads as they are write once and they couldn't read the codes off of them. Anyway. it was a costly fix and I'm hoping it's not a sign of things to come as I only had the car for about 6 months. Thanks to everyone who tried to help me.

THats good news.. So the new alarm modual has to re read the new ignition keys.. uuummm... I knew that each key is alocated to each modual but forgot that a new modual would not be able to read the old keys.. Thats an added expense and a bit of a bummer but 'alls well that ends well' and thats the main thing. Right, now get your clog down.