Major alarm/electrical problem
 

I had a proper nightmare with my 2000my Boxster S the other night. Bearing in mind that I've just had a bit of a run in with my neighbour recently, the last thing I needed was for my alarm to go off at 11.45pm waking up half the village. Of course it was hammering down with rain and the Porsche decided that it was happy to let me open the drivers door but the boot and front trunk stayed firmly locked. No matter what I tried, the alarm wouldn't shut up. I also noticed a very loud whirring noise from the area of the filler flap.

I remembered the emergency front trunk release cable and in the pitch black and with the rain still pretty torrential, I managed to whip off the wheel arch liner and release the lid, giving me access to the battery. I disconnected the battery, the horn and the alarm and tilt sensor. At last, all was quiet and I cleared off back to bed.

Next day I had a look around. The connectors to the alarm/tilt sensor were really corroded and the tilt sensor as full of water, so I'm guessing that this was part of the problem. However, once the battery was connected, I started the car only for it to run really roughly, with a distinct misfire that improved slightly with more revs. I don't think it would be much fun to drive very far like this.

I turned the car off as I had to go out and intended to have another look later on. So fast forward 3 or 4 hours. I pull on to the driveway in my wife's car to be greeted with a loud buzzing/whirring noise. Again its coming from the area of the Boxster's fuel filler cap and the car seems to be disable: boot and bonnet locked and car won't even attempt to start.

I' m really at a loss as to what's going on: has anyone got any ideas as to where I should even start to look? Any advice would be most welcome.

Boxsters Hate the Rain!
 

Sounds rather like the process I am still somewhat mired in: the ECU got soaked, I pulled it, cleaned it up, replaced it and now all the bits required for legal registration are working but the windows don't work, the locks don't work and I am afraid to try dropping the top.

That said, mine is a 1999 and I did read elsewhere that much of that problem had been fixed in more recent models. BTW, it was a lack of clear drainage that collected rainwater into the ECU area under the driver seat.

I will now post my own question that brought me here. It may be of help to you too.

Help! 1999 Boxster ECU, windows and locks
 

My 1999 Boxster got rained on and flooded. Lucky this never happened so badly in all these years, I guess.

Thanks to info here and elsewhere on the interwebs, I pulled the ECU and cleaned it up, as well as clearing out the puddle. It started working again and even runs smoother than it has in ages! BUT, the door and trunk locks and windows do not work.

QUESTION: Do I need to open up the covered boxy bits on the ECU and clean those to resolve this? Is that even doable?

I did check the fuses, no problem there.

What steps do I take to fix this as affordably as possible? (Like, if I have no alternative to a new ECU, where do I get one to install myself now that I know how? I have read that you can only use a brand new one because the access code (or whatever it's called) is only good one time.)

Appreciate any hints.