After a 2 hrs. fast drive. I parked my '07 911s for 30 mins. than restarted and it cranked slowly and did not start. I reset the key position and same result however i *think* I saw "Diagnostic Mode" displayed on the dash. The third restart was normal and everything fine, no faults.

The battery is 5 years old. I'm replacing it tomorrow just for drill.

If anyone has a clue, it might be reassuring!

 

Diagnostic mode shows up when battery voltage drops very low, on a dead battery for example. Might be battery, or starter/ alternator cable if it is difficult to start with a warm engine. Report back if the new battery cured the problem.

 

Thanks Rikky will do. New battery ordered. Barring bad luck I'll have it in tomorrow.

 

Interstate MTP-H7 (exact match) installed.

So...THAT'S how it's supposed to crank

Are terminal covers necessary? There were none however it is not hard to fashion something.

Thanks Forum