My 2006 C4 doesn't get driven enough, but I usually drive it at least once a week. I missed about ten days and it wouldn't start. I put a trickle charge on it overnight and it still didn't start. I was able to jump it off, let it run awhile and drove it, parked it, but when I returned there was absolutely nothing when I turned the key. We tried jumping it off from another vehicle with no success. Called AAA and got it jumped off. Again with the trickle charge and got it going, took it to a shop to have the battery tested. Tested Great. Took it home and put it back on the trickle charge for hours. Disconnected charger and it won't start. What can the problem be?

 

Got down to basics and cleaned battery cables and posts even though they looked clean. Tried charging with a charger and starting with no results. Tried jump start from another car with no results. I have a call into AAA to either jump start it or tow it to the shop. I'll update on the solution

 

Could be the starter cable. A known issue with the 06's.

 

If your battery is more than a couple years old and you let it get to that far a discharged state, it probably won't recover, even though you day it tested well. The surface charge may look good, but it may not have any capacity anymore. If you weren't having a starting issue before, the cable probably didn't go bad in a week, and its likely your battery. When it doesn't start, do you get a PSM failure message on the dash - that's the first error that shows up with a dead or disconnected battery.

 

2 possibilities here if you are convinced your charging circuit is healthy....1. As has been mentioned, is that the alternator to starter to battery cable needs replacing if you can not confirm that the cable has been updated from original. 2. The starter motor itself. Having replaced both on my 07 997 I would do them both at the same time if I were you as many parts of the install for both require removal of many of same engine bay parts. great time to replace air oil separator as needs to be removed to install battery cable properly.
Starter in my car had worn bearing at the pinion gear end of the motor and was seazzing as it heated up either from repeated attempts to start the car or from engine compartment heat . Result of replacing starter( with know to be good battery cable ) was a car that started as if it were
new with no hesitation on first turn of key. Also eliminated need for trickle charger. Car can sit for weeks without the need of a charger and still starts strongly.

 

I, too, had starting problems about a month ago. Thought it might be the ignition switch (which I bought but have not yet installed) or the clutch switch (which I was prepared to by pass), but apparently it was neither. I bought a new battery (I wasn't sure how old it was and the date was not indicated). All is well. If there is even a possibility that it's the battery, or if it is more than a few years old . . . . These car REALLY don't like a weak battery.

 

 

I had similar intermittent starting and non starting symptoms on an 07 TT 997.1 and it ended up being the starter itself. Replaced it and it starts everytime now. Always smart to keep car on a battery tender when parked.

 

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