And Then the Check Engine Light Came On!

"Check Engine, Visit Work Shop"
CHALLENGE ACCEPTED!

There I was last month, driving home in the rain from Carolina Motorsports Park  after some fun filled track driving, and WHOOPS!!! The Check Engine Light (CEL) came on to give me a heads up that something was wrong! Well dang it anyway! The car was still running and shifting fine, the brakes that I'd worked on recently were working normally, but the computer part of my car thought something was wrong. 

Luckily I was only about two miles from home, AND more importantly, the car was running just fine. So, I drove home, parked in the garage, and thought of all the bad things that could be wrong. Oh, and how much that might cost to fix! I was hoping it was just some kind of computer glitch caused by hard driving on track, or maybe the car's computer was amazed how fast I went and was just messing with me! 

Trouble codes: 
"Refer to service manual" -- Well, DUH!
"Communication PSM control unit (Drive)" -- OK, some part of the car isn't talking to another part of the car. It says (Drive) but it's driving OK!
"Communication instrument cluster (Display)" -- Cluster? It's working fine. 
"Voltage supply below lower limit." -- OK, this might be a real clue! Check the voltage. 

I visited my friends at York Technical College and the great instructors let me use a scan tool to read all the codes and try to figure out what was going on with the error message. There were codes basically saying that the various parts of the car weren't talking to each other, so maybe it was just an internal argument over oil viscosity or whether or not the Cleveland Browns would ever get into the Super Bowl. These kind of communication issues happen all the time!

The scanner wasn't giving me an instant or magical solution, so I figured I'd just erase all the codes, drive the car, and see if the CEL came back. Sometimes stuff like this happens, and again, since the car was driving fine, maybe that was it. No luck, the scanner I had wouldn't erase the codes. Oh well, I drove it home and sought out some more advice from people smarter than me (which is A LOT OF PEOPLE!)

Even more codes, great!

My region of the Porsche Club of America seemed like a good place to ask about this problem, and sure enough I got two folks that jumped right in. One suggested that since one code mentioned low voltage, that possibly I just had an old/weak batter, and that Porsches do not like low voltage. He felt that taking care of the battery would resolve the issue! That sounded easy!

These codes were fun, because they say the loudspeakers aren't working. BUT, they were working fine. Another clue that there was some temporary glitch and not a very expensive ruined car!

Another helpful club member said he had a different scanner and could come over and help me out! What a generous offer! We made plans to meet in a few days, and hopefully read the codes a bit more, or at least try the erase-it-and-see-if-it-comes-back method!

Luckily I also had a battery maintainer at home (thanks to NMS-South) so I hooked that up over night to see if the battery was OK. My records showed that the battery is just under 4 years old, so maybe it was due to be replaced. Fast forward to the next day, and VOILA! No more codes, and the car continued to run just fine like it had all along.  

Made sure the battery was charged, and BAM! NO MORE CODES! 
Why was I worried!

I don't think the hard driving or heavy rain caused the code, so maybe it is time for a new battery. My digital multimeter comes in handy for checking voltage, and after the little session on the maintainer the battery was right where it's supposed to be, over 12 volts while turned off. I'll keep an eye on that battery!