Silver_TT

2002 911 Turbo (US) On a recent hot day after turning off the car I got an error on the console indicating an error with the engine purge fan. This makes sense as I understand this is activated when the engine compartment > 172 F. Hooked up the Durametric and saw the following (see 1st attachment): P1675 Porsche fault code 658 - Fault - engine purge fan I understand this can be a few things including the fan being broken, the temperature sensor in the engine compartment, or fuses B4 and C5 and the relay, or even a DME fault. Of these possibilities I believe my issue may be fuses B4 and C5 or the relay because when I'm in the Durametric software and I try to activate the "Engine compartment purge fan" (see 2nd attachment) it doesn't do anything. However, I tried to activate the "Fan Stage 3" as another test to be sure there wasn't a communication error and I can hear that big blower fan go on just fine as I would expect. The only strange thing is that when I try to activate the "Engine compartment purge fan" I don't get a new P1675 error after the previous code has been cleared, which I would have maybe expected. I'm lazy, so I first decided to check the fuse box because it's the easiest to access. I popped out B4 and C5 (see 3rd attachment) and sure enough I can see that B4 is blown. Now my only question is: Are these fuses special in any way? In other words, can I run up to AutoZone right now and buy one (I'm assuming this is a 15 amp)? Or should I wait until Monday and drive to the Porsche dealer to specifically get one from them?

What White987S said. Also try Parts Heaven and there are a few others. Do a google search and most of them come up on the first page or two. Make a few phone calls; shoudn't be that tough to find and if multiple shops have them you can use that as bargaining power to get it at a better price. I've had good luck working with Neil at LA Dismantlers in the past. His price was fair and his description was accurate.

Also, there are something like 5 "slots" for key codes that can be stored in the vehicle's computer. So you should be able to see the existing ones in there.....and if this is the code for the key you are using, should be easy to match up.

I actually haven't done it personally because I only have a Durametric, but I believe it should be a 4 digit code and/or hexidecimal code on that card

This is the code needed to program your vehicle with the key remote it came with (can only be done with a PIWIS or PST2). It's a good idea to hang on to it. Your key fob is worthless without it if you ever need to reprogram or change vehicles, etc.

There are 4 o2 sensors on the US vehicles. 2 precats (1 left bank, 1 right bank), 2 postcats (1 left bank, 1 right bank). You would want to be sure you're looking at the correct parameters and that they apply to your vehicle as wvicary stated. But if these were failing they should be throwing a CEL. 100K is probably about the life of an o2 senor on average, but if the computer isn't throwing an error I'm not sure I would be overly concerned with it. The sensors aren't cheap................. .

which o2 sensors are you referring to? the pre-cat or the post-cat? the pre-cat sensors should oscillate ...... the post-cat sensors should remain much more stable

Yes, that's correct, I'm referring to the cable that runs from the alternator/starter/main junction. This is a very cheap fix as the cable is only about $50 and it's about a 2 hour job by the book. Logray is one of the best posters around here so I would defer to him, but just my personal advice having gone through something similar not all that long ago: 1. It's often sufficient to pseudo load test the alternator with it still in the car and it will only take 5-10 minutes to do. 2. If you do have a place like Napa or Autozone test it, know that their equipment is "pretty good" but not the most sophisticated. At least in my case they diagnosed the alternator as "OK" but then it turned out it wasn't working properly at specific RPM ranges. This likely would depend on what the exact problem is with the alternator (bearings, voltage regulator, etc) if there is in fact a problem with it. 3. Without more information, if I was betting I would say that this is probably just the wiring harness. However, if your alternator is that old or if you really think it's the alternator, you could consider replacing it preemptively as it's only about $350 and the alternator is going to need to come out to do the wiring harness anyway (so it's pretty much no additional labor). 4. Conceptually taking the alternator out is cake, however I found it really to be crammed in there and difficult to remove. If you do this yourself, don't forget to look at the workshop manual steps and specifically don't forget to give the main bolt a good whack after you unscrewed it a few twists. This will knock the flange on the alternator back and loose from the engine. If you forget to do this it can be a real bear to get the thing out...especially as it was in my 2002 that had been sitting in there attached to the engine for the last ~12 years. At any rate, the good news for you is that this problem probably isn't going that be that hard or expensive to fix.

Sounds to me like it could be the wiring harness based on the fact that you said it starts up just fine (cold) and then after you drive 10-12 miles (it heats up) it starts exhibiting problems.. These wiring harnesses are known to do this as they are prone to corrosion and the resistance builds as heat increases. I believe there might have been an updated part for this or TSB (don't quote me on that) but the Porsche guys around here tell me they replace a fair number of them (put it this way: they stock the part). Usually, if this is what your problem is, after you take the wiring harness off you can clearly see the corrosion. I would definitely check this before replacing the alternator as they will exhibit similar behavior. Dealer/indy should be able to diagnose this cheap, or if you DIY then you just need a simple ohmmeter. Conceptually this is very simple, although I found it to be pretty tricky in practice as everything in the engine is pretty tightly packed together. In my case it actually turned out to be both the alternator and harness, but I would say there's a decent chance it's just the wiring harness. Either way, this isn't a terribly expensive problem. Bosch alternator is only around ~$350 and the cable is ~$50.

Ok, I lied. Here are a few pics....

Cool, thanks as usual JFP! I actually sold my Bentley manual to a friend because it technically doesn't cover the Turbo model, but you have a good point there -- a lot of things are similar on the body so maybe I should pick one up again. I will post some pictures this weekend -- after I get the gas flap fixed. Car is beautiful, and it drives even better than I imagined. Can't really compare it to the 4S I had before. The interior looks pretty much the same but as soon as you start the engine it all stops there. Sounds different, feels different, clutch is totally different. The power at 4K+ RPMs is just mind blowing. The torque is unbelievable. Driving it is a complete rush.

Hello, 2002 996 TT. I was wondering if anyone has instructions on how to install the spring + plastic bracket for the gas thank door. I just ordered the parts today so it might be self explanatory but I didn't see where the spring would go for example. Any digrams or pictures would be greatly apprecaited. Thanks in advance.

First, I would clear the code and see if it comes back. In the mean time I would clean the electronic contacts as wvicary suggests. I have a recent post on this site which shows the location that the sensors plug into the DME, they are very easy to get to (drivers side is sitting right out, and passenger side only requires removing the air filter housing which is very easy). The information JFP attached showing how to interpret the o2 sensor readings will give you a very good indication if your cats are bad. For more information, you should read my recent post on this. It's quite lengthy but will give you a lot of education on the issues you're looking at.

I've seen a couple people on this site with 300K miles on their Turbo. You can get 996TT with 50-60K miles for ~ $40K in the current market. Pretty good deal.

Good news! I just heard back from AutoCheck about my open case on this and their research team was able to determine that there was an error when someone entered the mileage from the title. So they are taking it off the report as a black mark because it's an error... the emissions one is able to be taken off after we fax them a copy of the title...... so the records are clear and the score is looking a lot better now at 91!

I just talked to AutoCheck and they said the one of the decreases is from the Emissions department and they said that doesn't really count because they always make mistakes. It does look like in AZ or the auto auction the mileage was wrong. They are able to check on the auction and have created a case and will get back to me. They said otherwise if it was from the AZ DMV then the owner needs to get in touch with them to see if he can get it corrected. So sounds like no fraud, but obviously I just want a 100% clear and pristine record.

I am about to pay for and take delivery of a 2002 Turbo with 58K miles. The price is fair -- it's what Edmunds says the car is worth, and it seems right given the vehicles I have been looking at for the last few months. Mechanically the vehicle looks to be in good shape... there is just one thing. I ran a Experian Autocheck on it and it only scored a 76 with a warning that the vehicle does not qualify for Buyback protection. When I looked at why the score is so low it appears to be because of two things. 1. Loan/lien records - The owner told me he originally had a loan on the vehicle. I'm assuming it just hasn't been reported as paid off, which he's telling me it now is. 2. Odometer rollback/rollver. The thing here is that I actually see the mileage decrease TWICE, but both times by very small amounts.. and the car had also been moving from different states. Here are the readings: DATE MILEAGE LOCATION DATA SOURCE 11/03/2004 6,741 Maryland Motor Vehicle Dept 12/07/2005 11,338 Pacific SW Region Auto Auction 01/25/2006 10,723 Arizona Motor Vehicle Dept ***MILEAGE DECREASED*** 06/08/2006 13,099 Texas State Agency 10/02/2006 12,012 Texas Motor Vehicle Dept ***MILEAGE DECREASED*** 10/22/2007 28,235 Texas State Agency I'm guessing these were people at the DMV who fat-fingered or weren't that accurate with odometer readings. Isn't it almost impossible to hack the odometer and computer in these cars? Even if someone found out how to do it, why would you do this to a car with 10K miles on it just to rollback 500 miles. Doesn't make sense and strongly points to a clerical error. Is there a way to verify this or get it corrected? How would something like this affect the value of the vehicle later?? Should I be concerned with this and walk away from the vehicle?

I did it on my 996. Works and better than a broken one....but not as good as the original stem. Really sucks Porsche didn't sell these separately given that they are cheap plastic.

Wow, thanks man! I'm still trying to understand and absorb all of this but I can't tell you how incredibly helpful this is!

jpflip, thanks for chiming in. I've read a lot of your posts and you have a lot of good knowledge about the Turbo. I was wondering a few things: how much you paid to have the job done? Is there anything else that should be done at the same time presumably while the engine's out? Where did you buy the fittings for the 8 pipes that have to be welded (from your 6speed post)? How much were the parts? Is all the information in your 6speed post the complete list of information I would need to give my mechanic to have this job done properly. He hasn't done this specific job before but they do all kinds of crazy stuff and build racecars so if he tells me he can do it, I believe him. The guy's a rockstar. Thanks

Sorry to revive an old thread but, jcam, did you end up having the welding done? I'm faced with the same decision now and am looking for guidance from someone that's already been down this road..........thanks in advance

Thanks to you and others for your help. Couldn't have done it without you guys. Learned a lot about the exhaust system from this.

Problem was solved by replacing the cats. Now the post-cat sensors don't follow the pre-cat sensors at all. They stay very close to .7 V constantly on both banks, which means the cat is doing its job well. After I got the cats off I could shake them and hear the honeycomb broken inside. I guess when I was tapping them with a rubber mallet when they were still attached on the car, I must not have been hitting them hard enough because I couldn't hear it then. At any rate, if I had to guess I would say this must have been from vibration/age. The good news though is that the insides of the cats looked good so there is certainly nothing wrong with the car upstream. So the car is 100% back in working order, running like a champ.

If anyone has actually been through this and fixed the problem successfully please speak up. I plan to track some......so if this is even reasonably likely and having an instant coolant dump is a possibility, then I think I need to address it. Having a mass coolant dump could be extremely dangerous for myself and other drivers as coolant is very slick. Even driving on the highway this seems like it could be quite dangerous. I talked to a company called Shark Werks in CA and he said they recommend the "pinning" method + glued with Loctite. They told me they have had no failures when using this method. He said they have seen a number of the welding jobs that were done wrong or had pin-hole leaks....and therefore they don't recommend it. I guess if you go the welding route you really need someone that has done it many times and really knows what they are doing so they get it right. He told me, as a rough approximation, that the "pinning" takes about 8 hours of labor (depends on various factors so take that with a grain of salt). If anyone can actually give me some information on what the recommended fix is and who does it, I would greatly apprecaite it. Are other 996 TT owners concerned about this???

Interesting, don't know if it's from the same source but I heard that same rumor from a reputable source. I guess I will find out as I have a PCA track event here next month. From what I understand the welding method is preferable/better than the pinning method (since pinning doesn't keep it from leaking, it just keeps the hose from completely coming off) -- with the caveat that you have to have someone who knows what they are doing do the job...is that a fair characterization? I know neither is cheap as it likely means pulling the engine. The car I'm looking at has close to 60K miles, so from what you're saying, it sounds like there is a decent chance the previous owner has had to deal with this possibly at some point in the past.