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Cayenne 955-957 2003-2010 Series I
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Old 07-25-2012, 11:09 PM
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Lightbulb IF YOU'RE THINKING OF BUYING A 955/957 (2003-2010) - READ THIS FIRST!

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Old 07-29-2017, 10:32 PM
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Default IF YOU'RE THINKING OF BUYING A 955/957 (2003-2010) - READ THIS FIRST!

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Old 07-29-2017, 11:26 PM
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Default IF YOU'RE THINKING OF BUYING A 955/957 (2003-2010) - READ THIS FIRST!

Buying a 955-957 Cayenne? What to know what you might look out for? Please read this before asking in the forum. Then if your concern isn't covered - feel free to post in the forum.

Model History:
955, sold from 2003 to 2006 in the US. It was continued for 2007 in the rest of the world. There are various "variants" of this series, including a V6 powered one (sharing an engine with VW), a normally-aspirated V8 (generally called a /S) with 340HP and a turbo powered V8 making 440HP. A Turbo/S model was also offered - making 520HP. For the early 2007 year - Porsche (for the US) put lipstick on the P!G - and gussied up an /S with special paint and interior options - calling it the 2006 Titanium Edition. It was the last of the 995 series.

957, sold from 2008-2010 in the US was a "facelift" of the 955 series, with some additional engine options. The front exterior changed considerably from the 955, the interior and rear of the car (windshield back) was almost identical to the 955. Engines were bumped up in power with the Turbo now at 500HP, and a new 957 Turbo/S was introduced with 550HP. There was also a GTS - a better equipped /S, and the Transiberia - a 957 with offroad pretensions.
Pre-Purchase-Inspection (PPI): This is simply a good idea unless you are a fairly skilled mechanic, and have the time and place to check out the items below. Most Porsche dealers offer this service - with varying degrees of thoroughness. Before having it done by a dealer - ask what is inspected. I would hope it would include things like a driveline inspection, a compression test, and brake inspection. Even better is it includes a complete PIWIS diagnostic on the vehicle and a road-test. A PPI won't catch everything that might be wrong, but it's a good step in that direction. If you're buying the Cayenne for $4,000 - the cost of a PPI may not seem worthwhile, but if you can't afford to throw $4,000 away, you should consider the PPI as a sound investment.

If you have a private mechanic do the PPI - ask him what it includes, and perhaps hand him a printout of this posting so he has some ideas of additional items to check.


955: 2003-2004 were more or less "beta" years. There were a number of bugs, some electrical, some mechanical. Bugs diminished in 2005 and 2006 - hence the frequent recommendation to buy as new a 955 as you can afford.

955 - Transmission: The automatic 6 speed transmission in the early year 955's was known to be somewhat rough shifting. This was addressed by Porsche with a reprogramming of the transmission control unit (TCU), and eventually was found to also be caused by binding solenoids in the transmission valve body. Assuming the TCU updates were done under warranty, replacing the valve body in the transmission can be done by a skilled DIY'er for about $600, or have a transmission shop replace it ($600 + labor.) There was also a very weird failure where the electrical connector from the transmission to the wiring harness would leak and allow transmission fluid to flow up the wiring, eventually getting to the TCU and destroying it. It was rare enough that it isn't something to be concerned about, if it was going to happen, it already has.

955- V8 Engine Cooling Pipes: On the V8 engine cars, Porsche used ABS plastic pipes for running coolant from the front of the engine (thermostat box) to the rear of the engine (cylinder heads.)
Unfortunately the ABS used wasn't strong enough to take repeated heating/pressure/cooling cycles, and eventually one of the ABS pipes will split. When this happens the car will have to be flatbedded. The starter motor that lives under the pipes may be flooded and damaged, and if it was a chronic small leak that became a big leak, chances are coolant has dripped down on the torque-converter to transmission shaft and destroyed the seal.

Replacement coolant pipes were designed by Porsche in aluminum. Unlike what is often said on the Internet - Porsche NEVER installed the aluminum pipes at the factory, and no 955 came with the aluminum pipes.

There was a class-action lawsuit that partly reimbursed owners who had the failure, or preventively replaced the pipes before failure. You can no longer collect under that class-action lawsuit. The time limit for applications to it has passed.

How can you tell if the pipes have been replaced? There are various threads here that show how to view the pipes using a cell-phone and mirror. Using these tools you can just barely take a photo of the back end of the pipes. You could then post the photo here if you're in doubt if you can tell. Or if the seller has documentation that the pipes have been done - that's a good clue.

Cost - DIY around $600 for the parts. An independent mechanic will typically charge from $1600-2000. A Porsche dealer will easily be twice that amount.

Other costs associated with this failure:
If the starter is replaced when the pipes get replaced, the additional labor charge should be small, since the starter is right there exposed to the world and easy to get to. Rebuilt starters are in the $200-300 range. If the starter is replaced later plan on paying for about 6-8 hours labor, since the disassembly required for the pipe replacement is required.

If the transmission seal fails - this requires R&R of the transmission, some disassembly and replacing the seal. Typical numbers of around $2,000 are heard when this job is needed. Failure of the seal seems to be caused by allowing the coolant to flow down the V between the cylinder heads and into the torque-converter housing. It then hardens around the input shaft to the transmission into a rock-like substance - that eventually destroys the seal. It may be possible to avoid this fate by flushing out the V and down into the torque-converter housing while doing the pipe replacement - hopefully washing away any coolant before it gets a chance to transform into destructive hard crappola.

Note that the V6 models never had a cooling pipe problem. Porsche used a different design plastic pipe on the 957 series cars - and they are not known to have this failure.

Smart Move: Get the plastic pipes replaced BEFORE they go bad. They will go bad - it's just when that's the question. Chances are "when" will be when your significant other is driving the Cayenne down a deserted street in a questionable neighborhood. Chances are excellent she'll never drive it again after this happens. It will be "your" damn car, or being sold very soon after. Getting it fixed proactively means you get to avoid the expense of replacing the starter and replacing the transmission input seal.
955 & 957 Turbos - Coolant "T" Failures: To add to the list of cooling system failures these models may suffer from - the CTT and CTT/S have a coolant "T" used to send coolant down to the turbos - made from plastic - in a difficult to access location - that fails. It appears that every one of these will fail eventually - it's simply an under-engineered part.
Here is a great thread showing the problem, and offering info on replacing the T with an aluminum one that will never break: https://rennlist.com/forums/porsche-...-guidance.html

Smart Move: Take care of this proactively while the plastic cooling pipes are being replaced. It will never be more accessible. And your wife won't break down in that questionable neighborhood at midnight on a moonless night.
955 & 957 V8 and Turbo - Glued in cooling pipe failure: Both variants can suffer from coolant loss if an aluminum pipe, that is glued into the cross-over coolant manifold between the heads, at the rear of the engine, comes unglued.
While all of them don't fail, enough do to take note of the possibility. Various fixes range from replacing the entire coolant manifold (Porsche now makes one where the pipe is physically fastened in place), to drilling a hole in the manifold and pipe and using a screw to retain it, to using wire on the hose attached to the fitting - that is then attached to the manifold in such a manner that the pipe can't back out of the hole it's in. There are also people who have reglued the pipe in place, using a high-temperature epoxy such as JB Weld.

Most fixes can be done without engine removal but you will end up with bloody knuckles, there isn't a lot of room to work back there. On the direct injection cars - it may be necessary to remove the high-pressure fuel pump to gain access.

Smart Move: Take care of this proactively while the plastic cooling pipes are being replaced. It will never be more accessible. And your wife won't break down in that questionable neighborhood at midnight on a moonless night with werewolves prowling around and no cell reception. .
955 & 957 - Coolant reservoir: - The coolant reservoir splits on the seam and coolant leaks out.
Not as common a failure as the coolant pipes under the intake, but this failure happens on both the 955 and 957. The tank splits and coolant pours out. The reason is unknown. Is it simply a weak plastic weld at the seam, or is the system overpressuring and causing it to split. Dunno - fix is to replace the tank, and fill the system.

Smart Move: It's probably a good thing to examine the cap for the coolant reservoir, perhaps at every oil change. It only takes a minute. Take it off the car and examine it for any sign of buildup on the inner surface, and any openings into the cap. The cap has a blowoff valve that relieves excess pressure in the cooling system, but if it is frequently used, the coolant will dry at the vent port and eventually block it - meaning you now have no pressure relief. If you really want to be safe - add replacing this cap to the annual maintenance. It's inexpensive since it's also used in many VW vehicles (I've bought them for as little as $6.)
Good DIY from Pelican: http://www.pelicanparts.com/techarti...eplacement.htm

955 & 957 - Cardan-Shaft: The "cardan" shaft is what on other cars would simply be called a driveshaft. In a Cayenne there are two driveshafts - one to the front axle and one to the rear axle. Due to the length of the rear driveshaft, Porsche put a constant-velocity (CV) joint in the center of it - and supported this with a bearing, mounted in a rubber mount to the flange holding it into the vehicle.
With time and age - the rubber mount starts failing. The typical symptom of failure is hearing the driveshaft moving around when accelerating or decelerating. People have described it as sounding like a mad midget under the center console banging it with a hammer.

The "cardan shaft problem" isn't an "if" sort of problem, it's a "when". Climate and use of the vehicle determine when it fails, but it does always fail sooner or later.

There are various fixes for this condition:
The rubber mount or rubber mount and bearing are not available from Porsche. A rubber mount and bearing can be purchased on-line for around $80, and there are several guides to installing it. If a mechanic was to do the work - it would be 4 or more hours of work (it involves removal, disassembly and reassembly of the driveshaft.)

You can buy a brand new replacement driveshaft from Porsche - for around $1200. An independent mechanic will usually charge around 2 hours labor to replace it - unless it's difficult to remove - which they sometimes are. There is also available a single-piece carbon-fiber driveshaft for large $$$ - the advantage is weight and it doesn't require the center CV joint or bearing (or mount for the bearing.) It's probably nice for a custom build, but for a daily driver it appears to be overkill.

There is a company that makes a replacement for the "carrier" assembly that holds the bearing. It can be installed without disassembling the driveshaft or removing the driveshaft from the vehicle. Cost of the replacement is around $300. It is a DIY for a skilled DIY'er, or plan on about 2 hours labor for a good independent mechanic. They also sell rebuild cardan-shafts on an exchange basis, for much less than Porsche wants for a new one. The company is "Vertex" - a Google will turn them up.

There is also a very inexpensive fix. Search this forum for the term "Jimi Fix" - and spell it that way. This is what a very clever mechanic came up with to replace just the failed rubber without the need to remove the mount or driveline from the vehicle. It involves using heater hose and tie-wraps. While it might seem a hack or bodge - it works - and there are people driving around with 10's of thousands of miles on a Jimi-Fix without any problem at all. If you DIY - plan on about $15 for parts. A few hours labor. No heavy lifting, but it's easier to do if the vehicle is on a lift or at least ramps.

See: https://rennlist.com/forums/porsche-...with-pics.html for a great illustrated guide to the JimiFix - thanks to AGARubberDuck!

A great driveshaft thread: https://rennlist.com/forums/porsche-...dan-shaft.html - I've asked Dilberto if he can upload the photos instead of linking to them at the failed Photobucket (FU Photobucket!)
Smart Move: This one doesn't disable the vehicle. You can drive it - gingerly - to safety, so I'd suggest checking the condition of the rubber mount at every oil change, and replace it when you see any sign of cracking. Your wife can be told on the cell phone that it's OK to drive it home.

955 & 957 Cylinder Scoring: This plagues the 955 and 957 vehicles. It is relatively rare - but if it happens it's expensive, often costing more to fix than the vehicle is worth.
The problem is with a lubrication breakdown allowing the piston skirt on cylinder #5 to contact the cylinder wall - eventually resulting in destruction of the cylinder integrity. There are various theories on why this happens, and it appears it may be more common on vehicles that are regularly parked and then started in sub-freezing temperatures.
The fix - either a used engine, or getting the current engine rebored, new pistons and a complete rebuild. Used engines seem to be going for around $4,000 and up, and the labor to R&R the engine is at least 8 hours, and more for a turbo.

How to tell if this has happened? If it already has caused metal transfer from the piston to the cylinder wall and consequently scoring of the cylinder wall - there will be a distinct knocking noise from the cylinder. Most of the scoring takes place below the piston top when the piston is near bottom of the cylinder - meaning that using a boroscope isn't always able to catch it early. A compression test and leakdown will eventually give some clues. An oil analysis may also be a good idea as part of a PPI - excessive aluminum in the oil is a clue this is happening.
Smart Move: How to avoid it? Nothing specific that I've seen. Obviously good quality oil changed regularly will help. Not using too high a viscosity oil may help (since the high viscosity oil won't lubricate as well when the engine is cold.) Owning a turbo - which has an oil-squirter pointed at the bottom of the piston may help. Pray to the deity of your choice that it doesn't happen. Don't buy a used car from Antarctica. This may be one of the few upsides to global-warming.
955 & 957 - Headlight wiring: - Both variants suffer from headlight wiring problems. On the early 955 - the plug-in connector between the headlight housing and the body often didn't seat well, causing the contacts in the connector to heat up and eventually cook the insulation on the wiring. The insulation then falls off - and it wires touch - short circuits happen. Porsche sells a replacement section for the cable fairly inexpensively that helps avoid the issue. At the same time as the wiring outside the headlight is being cooked - the wiring inside the headlight is cooking. Same result - the insulation falls off - and any wires contacting each other or a component will cause a short circuit. If this happens - you'll need a new headlight(s). I haven't seen as many reports of this failure on the 957, but that might be just because they're newer and the wiring hasn't fully cooked yet. And just for fun - on the early 955 headlights used to fall out while driving down the road. That was a subject of a recall by Porsche. If it hasn't been done - get it done. To show how consistent Porsche is - they reintroduced this flaw with the 958 series, and that ended up also being a recall. Something to be said for German consistency (sometimes called stubbornness..) .
Smart Move: Use of a good contact cleaner on the connector may help avoid this. Some people have taken to dismounting the body side of the connector from the body and simply manually plug the headlight and now free connector together when they replace the headlight. That seems a reasonable and no cost preventative step that may be worth taking.
A link showing the problem, and a good photo of the wiring inside the headlight: https://rennlist.com/forums/porsche-...this-plug.html

955 & 957 - Air Suspension Problems: - The air-suspension system on the 995/957 models can be troublesome. It unfortunately uses outside air, pumped through a compressor to pressurize the system. This means that moisture can condense in the air stream from the compressor and cause corrosion of various valves. There are also failures of the air-springs, generally on higher mileage vehicles, or on vehicles that are lifted without putting the chassis in lift-mode (which turns off the system and locks it at the normal level.) The compressor can also fail due to excessive use - usually in response to a system fault that is causing a leak.
Rebuild kits are available for the compressor, and a replacement can be obtained at a more reasonable cost than the Porsche one by buying one for the VW Touareg - which people have found identical but priced more reasonably (it doesn't have the Porsche name markup..)
955 & 957 - Panoramic Roof Problems: - to be done - any SME who would like to help please contact me!

955 & 957 - Steering Column Failure: - Problem with starting the vehicle due to a failed component in the steering column.
The component isn't available as a part - it only comes from Porsche with a complete new column. When it's installed it has to be programmed to the vehicle. This isn't an "endemic" (they all do this..) problem, but it is a concern as the vehicles get older. Cost of a new column is ~$1,600. Cost for a dealer to replace it, including the column, around $4,000-5,000.

There are threads out there someplace that detail a way to get around the problem, since it appears a single plastic piece in the column lock is the cause of the problem (the piece triggers hall-effect sensors to indicate the column is unlocked, enabling the starter circuit.) If I can track those down, I'll add them to this thread. Here are some details on the issue - from another forum (you may have to be a member to access this): https://www.renntech.org/forums/topi...g-column-work/

BTW - if there are any subject-matter-experts on this issue - I'd love to hear from you. PM me please!
955 & 957 - Hatch Struts: - Non-power hatch - all models. With time and age - the gas struts that hold the rear hatch up start to fade. The first symptom is the hatch is harder to lift when the temperature starts dropping. Eventually they get bad enough that the hatch won't stay open in cold weather, and if you really let them go - the hatch won't stay open anytime. The failure is of the 4 gas-struts used to hold the hatch and the glass window up. The power hatch isn't subject to this failure since the major struts are actually an electrical linear motor, and don't rely on gas pressure.
Typically this can be fixed - at least for a while - by replacing the primary struts - that hold the rear-hatch up. Eventually it may reoccur - and that's a sign that the struts for the opening rear window have failed. Usual dealer prices to do this job are $600-1,000 (book is 4 hours labor). There is an excellent DIY to be found at: https://rennlist.com/forums/porsche-...ml#post9021110 - thanks to Michael S for it!
955 & 957 - 4-wheel Drive Error: - Message appears on the drive "Four wheel drive system faulty"
This error message means the traction-control module believes the stepper motor, that controls the transfer case has not responded correctly.

It can be caused by a bad stepper motor, or a stuck one. Or by a weak battery. For info on the issue - see: https://rennlist.com/forums/porsche-...y-warning.html - which also includes how to prevent it from happening. Cost of a new stepper motor from Porsche is around $700, and it's a fairly simple DIY. People have reported using the stepper motor from a VW Touareg that is apparently identical and a drop in replacement - available for less $$$.

Smart Move: Periodically - every month or so switch the vehicle into low range - this exercises the motor and apparently keeps it from sticking.
955 & 957 - Cabin Floor Flooding: - The cabin-floor flooding issue has occurred across all models of the Cayenne built to date (including the 958 series.) The issue is - a drain getting plugged up, and water filling the passenger or drivers footwell. The problem is - Porsche ran some serious wire bundles through that area, with splices in them. The splices can become intermittently non-conductive as they corrode due to electrolysis caused by water and electricity. This results in all sorts of interesting failures of various components throughout the vehicle.
How to identify the problem? If the vehicle hasn't been run in a long time, or hasn't been driven in wet weather, or hasn't had it's AC turned on - the leaks may not be evident. The only way to tell if this is happening (if the water level doesn't rise to where it's visible) is to pull up an edge of the footwell carpeting and stick a hand in. If your hand feels moist when it comes out - you have the issue. This is made worse by Porsche's noise obsession on the Cayenne. When you pull up the edge of the carpeting (use a trim tool to lever it out from under the doorsill) - you'll find 2" of dense open cell foam rubber. This foam rubber is capable of holding more than a quart of water before any actually appears at the carpeting. It also makes drying out the area difficult.

The possible leak sources are:

Passengers side: cowl drains (the cowl is the area the wipers live, and it gets all the water off the windshield), sunroof drains, and the HVAC - AC drain.
Drivers side: cowl drains, sunroof drain.

There are numerous threads addressing each of these leak sources - and how to find them and how to fix them. In general - cleaning the drains is the path to take.

IMHO the AC drain should be removed and cleaned annually when the cabin filter for the HVAC is replaced. Porsche now advocates removing the rubber flapper-valve at the end of this drain, allowing debris to more easily pass through. This drain can be fairly easily R&R from inside the vehicle when the HVAC filter is being changed.

The sunroof drain goes from the front-side corner of the "sunroof capsule", down the A-pillar (pillar next to the windshield), then behind the fuse panel, where it has an S bend in it, and finally down the inside of the outside kickpanel in the footwell. Cleaning it using compressed air will usually work, but some care is needed since it's also possible to blow it apart if there is a solid blockage, especially at the bottom of the sunroof capsule, or in the S-bend behind the fuse panel, where there are several press-together joints in the plumbing. Prevention would be to never open the sunroof, except to make sure the seal around it is in good condition. Some people (me for instance) have also used weed-whacker string to clear plugs. Use this with care since you don't want to push it through the plumbing in the S curve area. Testing the drain is best done by pouring a small amount of water into the catch basin in the sunroof capsule - and making sure it dribbles out the bottom of the vehicle. It will come out a bit behind the front tire and fender liner.

Cowl drains - drain a lot of water, especially in downpours, or car-washes. It mostly travels down passing around the hood hinges, directed down by foam-baffles that surround the hinges. These can plug up, especially on vehicles parked outside under trees by leaves and vegetative debris that the water washes down the windshield. There also are drains further down in the body that may get plugged up. These can be located by removing the wheel-well liner. Porsche now calls for the rubber seal on these drains to be removed, allowing larger debris to pass through unhindered.On my '06 CS, I had continuing flooding problems on the passenger side until I found that where the foam-baffle directed the water - there was a body plug missing that allowed water directly into the vehicle, behind the right side kick-panel. That had to be missing from the factory. I replaced the body plug - and had no more issues.

Threads that may be helpful:
GREAT photos in this one: https://rennlist.com/forums/porsche-...e-flooded.html

Smart Move: Check and clean ALL the drains annually. Consider doing it more often if the vehicle is parked outside under a tree. Or park it in a garage. There are also several plastic body plugs in the steel floor under the carpeting/foam-rubber, making an X shaped cut in these, allowing for at least some water to drain through them isn't a bad idea. That may prevent the foam from saturating. It does mean if you're doing river crossings with your Cayenne off-road - some leakage into the area may be an issue. Most of us don't do that.

Suggested reading: https://rennlist.com/forums/porsche-...l#post13710465 - covers the corrosion in the wiring bundles caused by floods in the footwells. This is quite common and easily diagnosed - if the car starts doing wacky electronics things (like multiple systems failing at the same time, or being impossible to diagnose because the scan tool can't connect to modules) - it's about certain it's time to get down and personal with the wiring splices in both footwells.

955 & 957 - Brake Booster Faulty: - A warning message on the dash indicates "Brake Booster Failure"
The actual failure isn't the brake booster (good - since it's $$$ and a PITA to change) - but a vacuum line failure that goes to the brake booster.

It's not a bad "fix" item - and usually any competent DIY'er can tackle it. For details see: https://rennlist.com/forums/porsche-...ing-light.html
Other useful threads:

Last edited by deilenberger; 03-29-2018 at 05:16 PM.
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Old 07-29-2017, 11:32 PM
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PLEASE send me PM's with your suggestions for additions, and any corrections. I'm sure a lot of people here know more about some of this than I do and I welcome your input.

The thread is closed - please PM me!

Thanks to AGARubberDuck and Petza914 for new additions! Thanks to Mudman for his initial thread - a summary of what to buy.
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Old 07-31-2017, 11:51 PM
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BTW - if there are any SME's (subject-matter-experts) who would like to contribute, please contact me via PM. You can write it up, I'll edit it to be in the form being used - and you get credit! How cool is it to share your info with fellow P!G owners!
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