Started up my 2006 997.1 a couple of weeks ago after sitting less than 3 days and the PCM screen showed the time as 12:00AM and the date as 01-01-2003. Drove it about 30 miles to see if it would reset without it changing. Reset the clocks per the manual but noted that the date function was managed by GPS and there wasn't a manual adjustment. This led me to think that the GPS antenna might have gone bad, but when i drove it again with the MAPS on the screen the cursor tracked to the road I was on. Also, the PCM screen, when on the radio function, periodically displays "Horn On". I'm guessing that only the dealer has the type of scanner that will troubleshoot this issue and I can't get an appointment for another month. I'm also guessing that the PCM head unit has crapped out and are very costly. Any of you folks had a similar issue??? I would consider installing an aftermarket head unit that has blue tooth and satellite radio, but I don't know of a brand that has a volume **** and i hate fishing around a touch screen when driving.

 

The older nav systems do not communicate well with the newer satellites. This began in 2019. My nav still works OK but the date is wrong and the clock is no longer kept accurate by the satellites. You can temporarily disconnect the nav unit and then change the date manually in the PCM but this will not last long after you reconnect the nav unit. Also, it is not easy to unplug the unit as there is not much room for your fingers. I reset the time every few months as well.

You can have the dealer do this for you ( for a fee ) with their PIWIS but this will not last long either.

 

Thanks for taking the time to respond. It sounds like we have the same issues, although you've been dealing with it for 3 years and mine didn't exhibit this anomaly until 30 days ago. I had a response on another Forum that it could be a Porsche update that wasn't digested by the older NAV systems. Regardless, I'll let the dealer fool with mine for a day or so and will then probably replace the unit with one that has blue tooth and satellite radio.

 

I corrected my post to indicate that the change made by the dealer would not last long.

 

Well, I'm a bit smarter now about this subject and a bit frustrated that Porsche has known about it for over 3 years and has not yet offered any solution. The one remaining question I have is in reference to the "Horn On" notation that appears on the dashboard and the PCM displays periodically. Stays on for a while and then goes away. Can that be related to the PCM issue???