1. Over Heating or Low Coolant Warning Light
There may be a number of issues here. The first relates to bubbles in the coolant system and the second to a drop in coolant level due to heat expansion in the flexible joints of the plumbing. For the first, try Porsche Pete's Boxster Board for a procedure to "burp" your system. For the second, there may or may not be an official fix - check your dealer and PNA. However, Porsche did something and it seems that cars from April 99 on, and maybe earlier, have the fix. Another possibility may be that under very hard acceleration coolant is actually temporarily sucked out of the reservoir to the point where the warning is displayed. Topping off the car and restarting may clear the light.
I have recently heard that one of the PAG factory machines had a fault up until April 99 that may have resulted in sub-standard casings and the resulting overheating problem. This is entirely unsubstantiated at present but if true would mean that cars built before April 99 will not all suffer from this problem. This has certainly been borne out by my own experience and that of others who have older cars but who have never experienced this unfortunate ailment.
Changing the ratio of coolant to water and adding Redline Water Wetter, may also be a fix. Reducing coolant and increasing water will cool better (water cools more efficiently than coolant) but this probably puts your radiator at more risk from oxidation. Different folks assess this risk differently and I do not feel qualified to give an opinion on it. However, this possible fix is certainly cheaper, if it indeed works, than some alternatives (oil coolers, additional radiators, etc).
2. Airbag Warning Light
Eric Sklut has this to say about the airbag warning light problem:
"The AIRBAG LIGHT saga...
Many '99 Porsche owners have experienced the Airbag Light problem - the airbag light comes on when one starts the vehicle, but instead of vanishing like the other warning lights, it remains on until the car is turned off.
This happened to me, and the story is worth reading by any Porsche owner. It is not intended to reflect negatively on Porsche in any way.
I took delivery of my '99 996 Cab in November '98. On day three, the airbag light came on and stayed on. Apparently, this has happened to other owners.
When I took the car to the dealer's service manager, t hey were aware of a problem with the airbag light, but only had one bulletin on the "fix" for it - change the seatbelt receptacles.
The PST2 (Porsche System Tester) indicated fault #45 - driver's side seatbelt. The service technician carefully replaced the driver's side seatbelt receptacle, reset the fault, and I left without the airbag light remaining on. About one week later, the light returned. When the technician checked the PST2, it again showed fault #45, but this time, the passenger side receptacle was changed.
A few weeks later, it happened again. By this time I was getting a little angry, and I asked if the dealer "tech line" had any resolution ideas. The only information coming from Porsche was a change in the seatbelt receptacles, and the new o nes should be on their way soon. The new parts have a "C" in their part #. Once the new ones arrived, my dealer replaced both front receptacles with the new ones. About two weeks later, the airbag light came on again. When I finally spoke with the district service rep, he informed me of a few similar instances where this problem was resolved by enhancing the contact point between the seatbelt receptacles and the frame of the car.
On this fourth fix, I had the solder enhancement added. About two days later, the light came back on. In frustration, I posted numerous questions to the various Porsche chat boards. I also began my own effort at contacting other dealers.
In my quest for an answer, another dealer told me that on early VIN# Boxsters there was a bulletin for changing the wiring harness under the seats. I asked my dealer and district service rep about this, and they agreed that it was worth a try. So, on the fifth try, the dealer pulled both front seats and replaced the wiring harness, soldering in new sections as per the '98 bulletin. To date, there has been no reference to any other failures of this magnitude.
I am glad to report that since the repair, I have put well over 3000 miles on the car and it is still airbag-light-free. It seems like mine was an isolated case, but I know this has happened to others. If your 1999 Porsche continues to show the airbag light there are some steps you should follow:
1) First be aware that the airbag module is STILL active, even with the light on
2) Take the car to an authorized Porsche dealer and have the car checked with the PST2 for faults.
3) If you get fault #45, ask the dealer to change out both seatbelt receptacles
4) If the problem comes back after seatbelt receptacle replacement, inquire about the wiring harness. Dealer should be aware of the early VIN# Boxster bulletin, but check to be sure. If not, have dealer contact their district service rep or PCNA.
5) Get the wiring harnesses replaced - takes about 30 minutes.
You should be fine after these fixes. As a footnote, as of June 1999, there have been a number of reports that there is a "new" fix for this problem. There is supposedly a new control unit that has been referenced as a replacement that will avoid airbag light problems in the future. Best to have your dealer confirm with PCNA on the best possible fix. I post this not to hammer Porsche - they really did work wonders - I had PAG and PCNA involved on this, and they were more than willing to do whatever it took to get it resolved - but I post this only in hopes that it may help other owners. A huge thanks to Steve Riley (PCNA) and Hendrick Porsche (dealer - Charlotte) for their efforts to get this problem corrected!"
3. Ghostly Windows, Creaking & Squeaking
If you come back to your car to find one of the windows about half way down, you have Ferry's Ghost syndrome! You will need to replace the window motor and relay/control under warranty. Dealers may take several goes to get this right. Personally it has happened to me only once and never again. Must have been the particularly strong garlic bread I had for lunch at Bravo's that one time...
Windows and interior bits are prone to squeaking. This may require reseating the front windshield and re-sealing the rear seals. An examination of the rear window seal should reveal if it moves significantly under pressure. If it does, reseal it. Where the interior door panel meets the door opening at the top is also an area worth checking - it is often too loose. Also I've recently noticed a faint and hollow rattling noise, kind of like a beetle sound, particularly when in 3rd. It took me a while to identify the source of the noise but finding it was the shift lever was a relief. Somewhat annoying and I'll have to get this looked at next time the car goes in to the dealer.
The clutch is also prone to sweaking. That too is a fix under warranty. Some have also reported that the clutch on early build cars grabbed too high or erratically. Depending on the month of manufacture, there is a revised clutch master cylinder that fixes this problem.
More on clutch problems below...
4. Oil leaks
There are mutliple reports of oil leaks from the main bearing seal. The fix is to replace the seal, apparently with a slight resetting of the seal placement and a dab of loctite. Persons suffering from this ailment should not be bamboozled by dealers into thinking it is normal for new 996's to leak oil. Some others have reported small amounts of a mysterious fluid under their cars - most often described as clear but with a viscous, oil-like quality. No-one quite knows what this is but candidates include: transmission fluid from the vent tube, power steering fluid, engine coolant, and a/c refrigerant oil. I've noticed this too but only on particularly hot days, which made me think it was condensation from the a/c that had somehow become oily from the underside of the car. Hopefully we will eventually work out what this is!
5. Clutch failure
There have been several reports of clutch failure/extremely rapid ware at very low miles (3-6,000 miles). Most dealers will not replace this under warranty and will claim poor driving on your part. Since some victims are long-time Porsche owners and owners of other clutch-sensitive cars, it seems at least possible that poor driving is not to blame. At the time of writing there is no official response to this issue.
6. Radio Buttons
The Becker radio/cass/CD is prone to button peeling. This usually requires a replacement unit and a change in radio codes (make sure you have the new ones). Warranty issue. Incidentally, it is believed that the replacement units are remanufactured rather than out-of-the-box new. The units can also have problems remembering what track is playing and have pretty poor AM reception.
7. Over-rev'ing (inc. rev limiter)
A fairly regular issue for newer sports car owners is their fear of exceeding the red line on the tach. Fear not! The 996 sports a rev limiter which simply cuts off the gas when you exceed redline, avoiding any damage to the engine. In manufacture all engines undergo several minutes of full redline operation as part of testing and quality control.
HOWEVER, it is still all too easy to over-rev the engine by shifting down inappropriately - aka, missing a shift. Going from 5th at high speed to 2nd (instead of 4th) will likely blow up your engine and no device currently known to man will prevent this. Be gentle and smooth with your shifter - smooth, smooth, smooth...
The speedometer is reported to be off (high) by around 10% in some cars. This affects not only speed reported but mileage, which can be significant over the length of a lease. The good news is that there is a software fix for this which should be available at all dealerships. Or do what I did - get a buddy or partner to drive their car at a set speed and tag along behind. I notice that when cruising on the freeway, I'm travelling at the same speed as other cars/drivers, who have presumably set their speed at a nice round number with cruise control.
9. Break In Period
Not really troubleshooting at all but it had to go somewhere. The manual says to keep revs under 4000 for the first 1000 miles. My dealer told me to ignore that and to keep revs under 5000rpm for the first 500 miles and then rev away to my heart's content. Opinion seems to favor sticking to the 4500-5000 'limit' for the first 500 miles or so, edging up to 5,500 until around 900-1000 miles and then going for it. It's important during the break in period to vary speed and revs to allow a "rounded" break in. Some have also suggested a rather early oil change at around 3,000 miles to get rid of any break in contaminates. See the earlier section on religious convictions and fluids. (Hmm, sounds like a line from Dr. Strangelove...)