Porsche 991 Dead Nav System: Common Electrical Fix?

Hi there! I had a fairly similar issue with my 2015 Porsche Cayman (I have some experience working on cars, but electrical stuff isn't my forte). Like you, my interior electronics were acting up, and it turned out to be a faulty interior light module. Took it to my trusted workshop, and they diagnosed it pretty quickly. The interior light was drawing too much power and messing with other electrical systems. They replaced the module and recalibrated the system, cost me around 85€ and fixed the problem completely. No issues since then! Which trim level is your 991? Also, are you noticing any warning lights on the dash? This info would help me understand if you're dealing with the same problem I had. Pro tip: If you're dealing with this, don't try DIY fixes, electrical issues in Porsches can be tricky and it's best to let pros handle it.

Thanks for the detailed response! Mine is the Carrera S model, and funny enough, I'm not seeing any warning lights on the dash. Last service was about 3 months ago at 145101 KM, and everything was fine until yesterday when this started happening. Really appreciate the heads up about not DIYing it, was tempted to poke around but will definitely take it to a specialist now. Honestly hoping it's just the module like in your case, sounds like a relatively straightforward fix. Did your workshop perform any diagnostic tests before pinpointing the issue?

Hey again! Yeah, I totally understand your concern, especially since it started so suddenly. When I had my issue, the workshop actually did run a full diagnostic scan first, it's pretty much standard procedure with these cars. They used their Porsche-specific diagnostic tool (PIWIS II, if I remember correctly) which helped pinpoint the module issue pretty quickly. In my case, they found that the interior light module was sending irregular power signals, which was causing the PCM (Porsche Communication Management) system to shut down as a protective measure. That's why both the nav and audio were affected. Since your symptoms are identical to what I experienced, and you've got no warning lights (just like my situation), I'm pretty confident you're dealing with the same thing. Quick update on my repair, it's been about 8 months since I had it fixed, and everything's still working perfectly. Honestly, the 85€ I spent was totally worth it. Just make sure you go to a workshop that's familiar with Porsche electrical systems, these cars can be pretty finicky with their electronics. One thing I didn't mention before, while they were fixing it, they also did a software update on the PCM system, which might be worth asking about when you take yours in. Better safe than sorry, right? Let me know how it goes when you get it checked out!

Thanks so much for all this information, it's super helpful! I've actually just called my local Porsche specialist and booked it in for tomorrow morning. I feel much more confident now knowing what to expect, especially about the PIWIS II diagnostic scan. Really good to hear that your fix has lasted 8 months without any issues too! I'll definitely ask them about the PCM software update while they're at it, makes total sense to cover all bases while it's there. You've saved me a lot of stress and probably money too by stopping me from trying to fix it myself! Will update you once I get it back from the workshop. Really appreciate you taking the time to share your experience in such detail. Thanks again!