Hello hope you can help with this awkward problem. I have a Porsche 997 Cab 2006. When its cold.. well cold for us here in Miami around 70 or below my speakers make a really loud noise when I unlock the car before I even open the door. The noise persists until the car is warmed up. This does not happen in the summer but happens on every single cold day. When this is happening the radio will not play. It turns on no errors but no sound. As soon as the noise goes away everything works fine the rest of the day. This also happens if I have the radio completely off. I'm assuming its the amp but why would the weather affect that? Any suggestions would be greatly appreciated. Thank you

 

It might help if you can describe the noise - a buzz, or hum? Intermittent during the warm up or constant noise? Grounding problems caused from a poor solder joint in the amplifier or electrolytic capacitors starting to age and fail could be the cause - I think that would be the place to start looking. Things expand once warm, so the fact it disappears after warming up is a leading indicator you can chase.

 

I agree I forgot to mention it sounds like really loud static not a buzz or hum. It alters between front and rear speakers depends on the day. It happens with the car off or on and the volume varies from a low sound to full blast. If I turn off the car and lock it it will eventually stop in 10 or 15 seconds when the amp shuts off.

 

After running a series of errands yesterday in 90 degree heat, I started the car and the rear speaker(s) suddenly emitted a deafening static-screeching noise. I immediately killed the power to the radio. I repeated switching the radio on and off, but the crazy screeching kept coming back — engine on or off. The radio volume control wheel had no affect on the screeching. As an experiment, I went into the PCM settings and adjusted the stereo fader control to 100% front speakers. Well, that completely stopped all screeching and the front speakers sounded perfectly normal. (Note: Even the slightest fader increment toward the rear produced 100% screeching.) I’ve only just begun researching this issue, but does anyone have a clue what might be causing this sudden glitch? Is there a separate amplifier just for the Bose rear speakers? Does a single amp control everything? Could this be a loose connector somewhere? I’ve had zero issues with my Bose system @ 64,000 miles. I’ll check it again today and report. Thanks to all!

 

My 2005 997.1 started doing this, but only when it was like 20 degrees. It progressed to less harsh static noise and at warmer temps.

Now there is no harsh static, but there is no sound at maybe 60 degrees and below. Been working fine all summer now 70's +

Have not been able to find out much about it other than threads with head unit vs bose amp's not working.

Thinking of an aftermarket option, but Im a little leery that that may not fix it and I'll be out $1000

Bruce in Philly has some good info.

PS - mine was briefly at start or turn on radio then ceased, not as long lasting as yours.

 

Update:
I started my 997S this morning and switched on the radio (fader still set to 'front-only' speakers) and then -- bracing myself for the worst -- I adjusted the fader control rearward just 1 notch: No screeching! So I bravely moved the fader to the midpoint (F-R balanced) position and all speakers sounded perfectly normal. While I'm wildly happy to report this news, should I be leery that there's a hidden amplifier issue that will reoccur? Okay, I'll be grateful and keep my fingers crossed.

 

If the 'screeching' had a sound like a 'chit-chit' or CD skipping, then that could be symptomatic of a problem with the optical connection to the Bose amplifier.

 

The rear speaker noise was an ear-splitting static sound blasting at full volume regardless of radio or CD player source. The volume **** had no effect except turning power on or off. Imagine the static noise an AM radio makes on an empty frequency at full volume.

 

Happen to have a bluetooth modification? I get a whine when my Bluetooth audio device is enabled. It's a whine that gets louder as my speed increases.
make the car sound like it's from the Jetsons.

 

That sounds more like ignition noise due to noise pick up in the cabling. That seems to be a significant problem in these cars.

 

If I had to guess with the noise blasting at full volume with no engine running, the amp has an intermittent leak in a filter circuit. You would have to pull it and have it serviced, but they are always easier to troubleshoot and fix when they have a hard failure. Alternatively, you could buy one and install it as a test. I don't think it's the PCM I think it's the amp based on your descriptions.

 

No mods whatsoever. I replaced the PCM LCD screen in January 2021 without any incident since. But it did occur to me that perhaps there’s a loose connection behind the PCM head unit. Easy enough to check. I have been considering installing a Bluetooth adapter behind the PCM, but haven’t gotten around to that yet given the wide variety of adapters on the market.

By the way, replacing the LCD screen wasn’t all that difficult, it just requires patience. LOL The bright new LCD screen manufactured by Sharp was identical in every way to the Porsche OEM screen ($89 Amazon).

 

Did you find a solution? I am experiencing the exact same issues with my 2006 C2s PCM with Bose. It started a few months ago and also seemed to be worst when cold. I also live in FL. I ordered a used Bose amp from Ebay and should receive this week. Hopefully it solves the problem.

 

This noise is almost certainly the amp in the trunk, the solder is contracting and that is the issue. I will bet that if it happens at 20, the radio comes back to life a lot faster than the days when its 5 degrees out. And once you hit a 30 degree day it doesn't happen at all. reflow the solder or grab a used amp.

 

I had the same issue with my stereo. It’s the original Bose unit that came with my car in 2006. I pulled the fuses to the unit, just so I could get in the car without being assaulted by the static screech.

Replaced my amp with a used one (thanks to jcmuniz) and the problem is solved.