jchapura

Porsche came out with a revised ignition coil pack 99760210404. It is thicker, presumably to mitigate issues with the earlier version.

Does anyone have long term experience or knowledge of the design life of the new unit? For example, should it be inspected more often than the spark plug change interval? Any other concerns?

ergi

Porsche don't make coils.
The coils are made by BERU and the reference is ZS178 for 997 phase1.
I have change the 6 coils on my C4S phase2 at 45000km, one was dead, i think the main problem for the coils is the temp,
they are very close the exhaust pipes, there is just a small metallic protection between coils and exhaust system.

Jim48

Yes, lots (too much) experience. First time replacement was at 46,185 miles (August 2013) - engine was missing badly under load. On one bank of cylinders the coils were heavily disintegrated, and the same thing was under way on the set on the other bank. All were replaced with part no. 997-602-104-00 . This set lasted until 68,188 miles (December 2019). At that time, the coils were beginning to show signs of starting to disintegrate so I had them all replaced along with the spark plugs. So this first replacement set lasted a bit over 20,000 miles. The replacements were part no. 997-602-104-04. At that time, I was told that these were an upgraded coil that would solve the problem. I have not done a lot of driving in the past two years so the mileage is now nearly 75,000 and I have not had any problems so far. Hope these last a lot long than the others as the labor cost of changing them is high.