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Car flooded now wont start. HELP.

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('97 boxster 2.5 <70k mi)

so my convertible drains clogged up and flooded the driver side floor.

-i removed the interior carpet so it could dry - cleaned out the drains and vacuumed out the water.

-then i tried to start the car and of course it wouldnt start. the alarm module under the drivers side seat had been completely submerged underwater.

-i tried plugging in another module from a '97 and tried scanning the car, but all the modules say that they cannot communicate.

-i have dash lights so im pretty sure the ignition switch is good so i know that the key is in the on position. i had replaced it less than 6 months ago.

-checked all the fuses in the fuse panel next to the dead pedal.

-checked the big 40 amp fuse in the trunk (not sure what thats for.. maybe for fans or a/c compressor)

-im positive that the battery is good. i had a charger on it just in case while i was checking out the car.

so my question is.. anything im missing? any fuses i didnt check? some kind of immobilizer system that locks up the modules? some kind of coding that im supposed to do to the module before installing it?

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You can try drying out your immobilizer and praying.

If it has shorted out hen you have to get a new one AND have it programmed to your keys and DME.

already tried that. but didnt help. so i took it apart and cleaned out all the green gooey gunk that got spread out inside there. dried it all out and reconnected it but didnt work. thats why i got a module from another 97 with the same part numbers.

as quoted above, when i reconnected the 'new' module and scanned the car, i had no communication to any of my modules.

shouldnt i at least be able to communicate with my modules even if i have an alarm module from another car? better yet, even if i have a flooded module still in my car, shouldnt i be able to communicate with any of my other modules?

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shouldnt i at least be able to communicate with my modules even if i have an alarm module from another car? better yet, even if i have a flooded module still in my car, shouldnt i be able to communicate with any of my other modules?
No. Any immobilizer change requires reprogramming using a PST2 or PIWIS and your car's unique IPAS code (available only from Porsche).
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You can try drying out your immobilizer and praying.

If it has shorted out hen you have to get a new one AND have it programmed to your keys and DME.

BTDT thrice. Submerged completely 2. You can do it as long as you get it out within a day or 3, scrub the board of with fine wire brush. Give cable conectors a good cleaning....Drills holes in the floor(gasp). Never know whem you'll find the leak or when you'll get another.


Yes prime the holes too.

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yeah.. already tried scrubbing and drying. hasnt worked yet... but ill try it again. otherwise i have to back to the dealer? <_<

thanks for your replies guys.. any other suggestions at this point would be greatly appreciated

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Too bad. A few people have been able to get the control unit under the seat out and apart quickly enough to salvage it. The less time it is exposed to electricity and water the better the chance. What a dumb place to put it.

A long time ago I posted how to replace the control unit with a used unit from a donor car, as I had just spoken to Peter Smith to see if this could be done. I forget the details. First, you have a 1997 and the replacement must be from a 1997, as 1997 was the "strange" year. Your replacement is from a 1997 so that is good.

Your original unit has a code in it that matches a code in your DME. A used unit is going to have a different code than your DME so that is why they cannot communicate.

You cannot change the code in the used unit to match your DME, but you can change the code in the DME to match the used unit. But you need the code from the used unit. This means you need the VIN the used unit came from. With that VIN you get the code from Porsche for the donor car, and put that code in your DME to match the donor control unit.

It has been a few years since the post, so this is from my failing memory.

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I found the post from 3 years ago. http://www.renntech.org/forums/index.php?s...hl=control+unit I bought a used unit but I made sure the seller gave me the VIN the unit came from.

If you have the alarm option then you also have to deal with the codes for the remotes. If your flooded unit is not too damaged then with a PST2/PIWIS you can take the codes out of the unit and transfer them to the replacement. Otherwise, you would need the paper tags that came with your remotes, and almost no one has those. Those paper tags have the code.

If all else fails, you have to buy new remotes.

Something like that anyway. Professor Holyoak is better at this stuff than me. It is an expensive headache when that control unit gets fried.

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I think this is the biggest problem on a 986. That dumbass Porsche engineering to locate this fragile electronic component at the bottom of floor for a roadster!

I've seen this happened more than 100 times now. U might get lucky if your fuse was just popped or few hrs of tracing here & there .

Once your computer is ruined like here, this can be a very frustrating & spendy nightmare! Your car won't run - who knows how many days, gotta order the computer module + new key because your stupid computer will never recognize your old key as TP mentioned + reprogramming for DME + more programming.

My blue fuse was blown about 2yrs ago and floor was little damp. I don't mount my module on the floor anymore, using a couple of wire ties now it is just floating to the bottom of my driver seat.

Ever since she is just fine!

Edited by juniinc
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thanks so much for all the helpful replies guys. thanks for the link tool pants. id really like to go with your advice, however the module that i borrowed was only lent to me by a generous friend and is not mine to keep.

i already have a module on order and when i recieve it, i need to make an appointment at the local dealer.

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is this true?


"When the alarm module is flooded, it also shorts out the door lock actuators, front and rear hood release actuators and fuel flap actuator.

You can only swap the alarm module (from another car) with the DME and keys.

I would contact your insurance company. The interior needs stripping out and drying, doors stripped out for new actuators, hood and fuel flap releases replaced, alarm module replaced and the system programmed. Repair cost will be high."

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That is pretty much true.

If the immobilizer/alarm/central locking control box is badly damaged (by water or accident) then none of those systems will work and your car can not be started.

In a rare case or two the owner has been able to open the box clean and dry out the circuit board and get it to function again.

If not, then you are stuck with buying a box and paying a dealer (or shop with a PST2) to program the immobilizer (to the DME) and the keys to the new immobilizer.

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  • 6 months later...

I seem to be having a prob with my alarm. Everything works fine, however, the alarm will sound about 20-50 minutes after the car is locked. I have check all doors, trunk and hood to ensire closure, but still goes off.

Any ideas what could be wrong? This is very strange!!!!

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