All gone wrong

Well all of a sudden it's all gone wrong and I really could do with some help. My C4 was intermittently running rough (sounds like a 2cv) now suddenly it is doing it all the time and the check engine light is on.........is this likely to be a coil? If yes do you think it is a job for someone half practicle or is it a garage job? Second issue, all of a sudden the locking and alarm have stopped working, was working one minute but not the next, tried spare key no joy. The little light on top of the dash is not lighting up at all, checked fuses etc, pulled alarm one out and the alarm went off....any ideas. Would really appreciate some help. Thanks Stuart

It looks like you have two problems... one of them is battery and the other is possible coil issues. Did you have any smoke, oil burning etc ????

Does sound like a coilpack, if you don't have access to piwis etc you could try disconnecting one coil pack connector at a time and starting the engine to see if it gets worse, if when removing one it stays the same then that coil or plug is shagged. I need someone with more experience to tell you if there is any possible damage this could do though before you try it. To replace coilpacks & plugs really isn't difficult, just fiddly cos of lack of space, find a 5" socket extension or 2 x 3" together plus your plug socket and a stubby ratchet and you're done. Alarm issue is grief, I'm struggling with a central locking problem which just started like yours, again piwis to diagnose but pulling the fuse without the ignition on will just cause the alarm to go off (def not the fuse though!) does the remote work at all? Try a quick double press. Does the central locking work by manually turning key in lock?

I agree it sounds like two problems, and you will save yourself a lot of time and grief by getting a diagnostic check done, but it does sound like coil packs. It isn't a cabriolet by any chance? Are the carpets damp under the passenger seat?

Thanks for your replies guy's. Yes it is a cab but the carpets don't seem damp (i think) I will double check, what is the answer if they are damp? Have tried pressing the key fob in every way possible, the key still locks the car if you put it in the door. What is the best place to buy coils from aftermarket, might have a dabble myself next week? Also...what is piwis? Thanks for your knowledgable help.

Check very carefully under the passenger seat, as that is where the alarm control module is situated - very conveniently at the lowest point of the floor pan. If you have a leak (blocked water drains, etc) the water gathers at this point, floods the unit, and causes all sorts of problems with the alarm. Try Euro Car Parts for the coil packs, but there are plenty of places who sell them. GSF, Porscheshop, Forest Fine, etc, etc. The PIWIS is the Porsche Integrated Workshop Information System, or in plain English, the Porsche diagnostic tester. There aren't many testers which will read fault codes on all control modules of the 996 - PIWIS, PST2 (it's obsolete predecessor), Autologic - all of which are professional level tools, and the Durametric tester, which is about the only DIY tool. HTH