Failing Porsche 997 Electrics: DIY Fix or Pro Help?

Had a similar issue with my 2009 Porsche Cayman S last spring. The symptoms were almost identical, weak starts, flickering lights, and unusual electrical warnings on the dash. Took it to my trusted mechanic and turns out the Motor Control Main Relay was failing. It was causing intermittent power delivery issues throughout the electrical system. Got it fixed at an independent Porsche specialist. The repair involved replacing the relay unit and checking the entire charging system to ensure no other components were affected. While they had it open, they also tested the alternator and battery, both were fine in my case. It wasn't a huge job, but definitely needed immediate attention to prevent potential damage to other electrical components. You really want a mechanic who knows Porsches for this kind of work, there are quite a few connections to check and specific diagnostic steps to follow. Been running perfectly since the fix, no more electrical issues whatsoever.

Thanks for sharing your experience! This sounds exactly like what I'm dealing with. I'm actually going to have it looked at this week. Do you remember roughly how much you ended up paying for the relay replacement? And has everything stayed solid since the repair, or have you noticed any other electrical quirks pop up?

Hey there! Glad I can help with an update. Yeah, the final bill came to 130€ for the Motor Control Main Relay replacement. It was money well spent because the car's been running like a dream since then, no more of those annoying electrical issues at all. The terminal 15 interruption problem that was causing all those symptoms is completely gone now. I'm super happy with how it turned out. Haven't had a single electrical quirk since the repair, which was a huge relief. My starts are strong, lights are steady, and those pesky warning lights are history. After my experience, I'd definitely say if you're seeing similar symptoms, getting that relay checked is the way to go. Just make sure you've got someone who really knows their way around Porsches handling it. My mechanic really nailed the diagnosis, and it's such a relief to have it sorted. Let me know how yours turns out, I'm betting it'll be the same issue!

Hey! I wanted to update everyone on my situation! Finally got my 997 back from the shop yesterday, and you were spot on, it was indeed the Motor Control Main Relay. Found a great independent Porsche specialist who really knew his stuff. The total came to about 150€, which included a thorough diagnostic check of the entire electrical system. The difference is like night and day! The car starts up strong every time now, no more flickering lights, and all those annoying electrical warnings have disappeared. Had a nice long drive this morning just to make sure everything was solid, and it performed perfectly. Really appreciate everyone's input, especially about the relay issue. Saved me from going through multiple mechanics and unnecessary repairs. Amazing how such a small part can cause so many problems! If anyone else runs into similar issues with their Porsche, definitely get that relay checked first. Thanks again for all the help! Nice to have such a supportive community to turn to when these things pop up.