2016 Cayman GT4 Exhaust Manifold/Oxygen Sensor Welds

[NickG]

I have no idea if this is a first for anyone reading this, but thought I would share with the community. Note, I am not that mechanically minded, but this is what I remember being described to me by the technicians (as it was a first for them, too).

I was instructing at Club Motorsports, NH this Fall, when my exhaust suddenly blew, while I was out on track. As I backed off, I got a backfire and I cruised into the pits. I shut it down, after quickly trying to determine where the leak might be. It was difficult to tell specifically where the hole in the exhaust was, but I did get a warning sign saying “Engine Control fault. Consult a workshop. Driving Permitted”. So the next day, I drove the car at 50-55mph to my independent Porsche mechanic (90min drive).

Once inspected, they found the metal weld around one of the O2 sensors on the OEM exhaust manifold had cracked (bank 2), blowing hot air in/around the manifold area (photo 1-2 – not the best shots but you can see the crack). After repairs were made using an OEM replacement manifold, the test drive prompted an engine warning light and hesitant acceleration. After another 30mins of investigation, it became apparent that the O2 sensor harness that ran close to the manifold had been melted by the extreme heat and some wire had shorted out causing the mixed signals to the engine management system.

It was also thought that with the harness being under tension as it is slotted around 90 degree turns (see photo 3), exacerbated the situation.