The 955 and 957 Porsche Cayenne were available with two different suspension options. First, there was the standard coil-spring and shock setup available on all models, except for the Turbo. Then there is the advanced, self-adjusting Cayenne air suspension that came as standard on the Turbo and was an option on other models. Despite being an optional system on most models, the air suspension is common on the first-generation 9PA Cayenne. Since the air suspension is more complex and requires a bit more service than the standard coil spring suspension, we're going to focus primarily on that, covering common Porsche Cayenne air suspension problems, repairs, and more.
Porsche Cayenne Coil Spring Suspension (955/957)
First, we'll briefly touch on the standard 955/957 Cayenne suspension with traditional coil springs and shock absorbers. Porsche Cayennes equipped with standard suspension have a fixed ride height, without any kind of adjustment. Because of the overbuilt design of the Porsche 9PA chassis and robust character of the suspension control arms, mounts, and various ball joints and bushings, the non-air ride Cayenne suspension is extremely low maintenance and generally very care-free. There are essentially only two primary components that can wear out: shock absorbers and springs.
Technical Specifications:
- Shocks: Standard dampers, non-adjustable
- Springs: Coil spring, fixed ride height
- Years: 2003-2010
- Models: Porsche Cayenne Base, Cayenne S, Cayenne GTS
Recommended Service Intervals With Standard Suspension (955/957 )
- Check suspension fastener torque: 20,000 miles
- Visual inspection of springs, shocks, tie-rods, and bushings: 40,000 miles
- Recommended shock absorber replacement: 80,000-100,000 miles (varies)
Porsche Cayenne Coil Spring Suspension Problems (955/957)
Shocks and Struts
The 955 and 957 Cayenne shocks and struts will be the most likely component to need replacement. While they will last quite a while, the shock absorbers on the Cayenne will eventually wear out. Exact mileage will vary depending on where you live, how you drive, and the kinds of roads you frequent, but around 80,000-100,00 miles is a good interval to start checking them closely.
When the shock absorbers on your standard suspension Cayenne begin to fail, you will typically start to see an excessive amount of dirt and oil on the shock absorber housing. As this worsens, you will notice a few things when you're driving the car. First, it will feel a bit more unstable and planted, especially at higher speeds and over larger bumps. When you hit larger dips, the truck will "porpoise" and continue to bounce as you drive. Symptoms of a bad Porsche Cayenne shock include noise, and in extreme cases, you'll start to see uneven wear on the tires, called cupping. Cupping is caused as the tire bounces along the road rather than making continuous contact.
The 955 and 957 Porsche Cayennes equipped with a standard coil spring suspension are easily identified by looking at the center console. There is only one switch to control the four-wheel-drive system on a Cayenne with standard suspension, rather than additional controls for ride height and shock absorber settings. The shock absorbers on the standard coil spring suspension models are 'traditional' non-adjustable dampers and do not feature the Porsche Active Suspension Management (PASM).
Coil Springs
Although rare, coil springs can break or crack. When this happens, you will need to replace the bad spring with an OE-equivalent spring. We typically recommend replacing springs in pairs on a specific axle. If you have a broken right rear spring, we recommend replacing both rear springs to ensure an even ride height and proper handling and towing capacity.
Common symptoms of a cracked or broken Cayenne coil spring include lower ride height on one corner of the car when parked on level ground and/or a visibly broken spring.
If you use your Cayenne for towing, you'll want to keep a close eye on the condition of your rear suspension. The extra loading will put a lot more wear and tear on the shocks, springs, and bushings, and these will wear out more quickly. You should also visually inspect various bushings, ball joints, and front steering tie-rods for signs of cracks and tearing in the bushings and boots. If you notice any kind of a loose feeling in your Cayenne's steering, it is a sign that one of these components could be worn and need replacement.
Replacing shocks on a Porsche Cayenne is relatively straightforward and requires normal specialty tools such as a spring compressor and a properly rated jack and jack stands. It's important to keep in mind whenever you're working on a Cayenne that it is a weighty truck, near or over 5000lbs, so you'll need a 3-ton rated jack and jack-stands to safely tackle a job like this.
Porsche Cayenne With PASM Air Suspension (955/957)
A Porsche Cayenne equipped with the PASM Air Suspension is one of the most versatile and capable SUVs ever made, and when the 955 Cayenne was introduced in 2003, it did things that no-one thought a 5,000lb truck could or should be doing. While a Porsche Cayenne air suspension fault does require a bit more time and potentially a greater cost to diagnose and repair, the advantages of the air suspension are impossible to deny.
Air suspension was optional on all 955 and 957 Cayenne models and standard on all Turbo and Turbo S models. The system consists of four air struts, an air pump, an air tank/accumulator, valves to control air pressure to the struts, and a computer that controls all of that. 955 and 957 Cayennes equipped with air suspension also feature Porsche Active Suspension Management (PASM), Porsche's adjustable shock absorber technology. The combination of the active self-leveling air suspension and PASM constantly working together are tough to beat, as they give the Cayenne the best handling and grip, no matter what speed or situation, on or off-road.
955 and 957 Porsche Cayennes equipped with active air suspension and PASM have ride height, and shock absorber controls mounted just to the right of the 4WD controls. 957 Porsche Cayenne models can also be equipped with Porsche Dynamic Chassis Control (PDCC). PDCC adds hydraulically controlled sway bars to the mix, giving even more control and better on-road handling. Off-road, the PDCC sway bars can automatically disconnect to allow for more suspension travel and articulation at lower speeds.
This is similar to the special Off-Road Package option that adds a locking rear differential and active/auto-disconnecting rear sway bar, but full PDCC is only available on 957 models. How to tell if a 957 Cayenne has PDCC? A 957 Cayenne with PDCC has all-silver buttons and switches for 4WD, air-suspension, and PASM controls, versus silver switches and black buttons for non-PDCC models. Since it uses hydraulic fluid and a reservoir with an integrated filter, the Cayenne PDCC reservoir replacement should be done every 60,000 miles as part of the PDCC service.
The Cayenne's air suspension has an adjustable height range of roughly 4.5" with six selectable preset ride heights. It also makes adjustments based on speed, and at 130mph or greater, the Cayenne moves a full 1.5" lower than its standard ride height. There's also a special off-road mode that increases ride height by 1", giving almost 11" of ground clearance. At this extreme setting, it is said that the Cayenne can handle water-crossings of just under 22" of depth, which is pretty unheard of when it comes to 'luxury' SUVs.
Technical Specifications:
- Range: 4.5" +/-
- Ride height: Approximately 6.25-10.75"
- Shocks: PASM electronically controlled dampers
- Springs: Air spring shocks/struts, self-leveling and adjustable
- Years: 2003-2010
- Models: Porsche Cayenne Base, Cayenne S, Cayenne GTS, Cayenne Turbo, Cayenne Turbo S, Cayenne S Transsyberia
Recommended Service Intervals For Porsche Cayenne Air Suspension (955/957)
- Check suspension fastener torque: 20,000 miles
- Visual inspection and operation of air suspension: After 10 years, then every 2 years
- Visual inspection of tie-rods and bushings: 40,000 miles
- Recommended air shock/strut assembly replacement: As needed
- Check hydraulic fluid level for sway bar/PDCC:Every 20,000 miles
- PDCC reservoir replacement: Replace every 60,000 miles (integrated filter)
Porsche Cayenne Air Suspension Problems (955/957)
With all of this air and electronic trickery to control the delicate balance of 5000lbs plus, some parts will need to be repaired or replaced to keep everything operating at tip-top condition. Here's a list of the major Cayenne air suspension problems that you are more likely to encounter. It's important to note that any number of these issues will result in a Porsche Cayenne chassis system failure fault message in your instrument cluster, but further diagnosis will be needed to figure out exactly which problem is causing the fault. Parts for the Cayenne S air suspension, Turbo, Base, GTS, and Turbo S are all more or less the same, without any significant difference in components or pieces.
Suspension Air Compressor
One of the most common failures with Porsche Cayenne air suspension is the air compressor. The air compressor doesn't constantly run as the suspension is making adjustments, but only to resupply the air storage tank. The Porsche Cayenne air compressor location is up at the right front corner wheel housing/door hinge area, underneath the underbody plastic. As it's an electric motor, the pump can simply fail and no longer operate, requiring replacement with a new or remanufactured unit.
If your Cayenne is no longer able to maintain proper ride height, it could be a symptom of a bad air suspension pump. Since the tank holds residual pressure, this doesn't happen all at once but over a more extended period. You will see a chassis system failure fault if your air compressor fails. There is a power relay that can also fail and make it appear as though the compressor is bad, so it's important to verify it's receiving power before simply replacing the compressor.
Valve Block
The valve block is the physical control hub for the Cayenne air suspension. After the compressor fills the air tank, the air tank supplies air to the valve block, which physically sends the air to each individual air strut. As an electro-mechanical component, the valve block can fail in terms of a physical air leak or an electronic failure.
If your Cayenne air suspension valve block fails, you will have a chassis system failure fault, along with a loss of ride height control on one individual corner, the front or rear axle, or all four corners.
Air Shocks & Struts
The Porsche Cayenne air suspension shocks and struts are robust and don't fail with great regularity compared to some other makes and models, but it is a possibility over time. Typically they will develop a leak at the air hose connection, or very rarely, at the airbag itself. Check the airbag for signs of serious dry-rotting and cracking. The pressure relief valve can also fail, causing too high a ride height, but that is less common.
Signs of a bad or failing air shock or strut on a Porsche Cayenne include a loss of ride height at one corner of the car, typically over time or after the car has been sitting. You may notice a slight air leak more quickly by paying attention to how often the air compressor runs. If the compressor is running more than usual, it could be a sign of a small air leak in the system. It will be highly unusual to see a pair of air shocks or struts fail simultaneously, so if both left and right sides at either the front or rear seem to be affected, it's more likely some other issue. You will typically see a chassis system failure fault when you have a bad air strut or shock.
Ride Height Level Sensors
As 955 and 957 Cayennes continue to age, certain components are starting to become more common in terms of routine failures. The ride height level sensors are one of these components, especially in terms of how and where you drive your Cayenne. If you live in the Northeast or any other area with lots of road salt and snow-melt chemicals, the level sensors live a decidedly hard life. Physical and electronic failures can result in total failure of the sensor or incorrect readings being sent to the control module.
If one of your Porsche Cayenne ride height level sensors fail, you will typically see an incorrect ride height at the corner with the bad sensor. Depending on if it's a total electronic failure or just sending wrong information to the control module, this could be too low of a ride height, or it could be too high. Keep in mind that since the controller is not necessarily aware that it's seeing the wrong info, you may not see a chassis system failure fault with a bad ride height level sensor. Double-check everything on that corner, including the level sensor, before assuming you need to replace the air strut/shock or some other component.
PASM/Electrical Connection Failure
The Porsche Active Suspension Management system is integrated with the air suspension system and controls, so it is possible to have Cayenne PASM failure on an air shock or strut and not have any issues with the airbag or ride height. Porsche Cayenne PASM dampers are electronically controlled by the suspension control unit, and damping is able to be increased or decreased as needed or set by the in-cabin controls. The Cayenne PASM electric harness can be damaged and need to be replaced, or the connection at the shock can also fail.
Symptoms of a bad shock absorber or bad electrical connection include PASM and chassis system failure faults, along with a loss of damping control or adjustment, but not any loss of ride height. This can be caused by corrosion inside the PASM connectors, so it's important to check those before replacing an entire shock or strut.
Air Lines & Hoses
Since they are physical components, the Cayenne air lines and hoses can sometimes be damaged or fail, causing a loss of air pressure and therefore ride height. If you take your Cayenne off-road frequently or you've been working on or near any of the air lines or air shocks and struts, it's important to give a good visual inspection and look for signs of damage or impact.
A bad air hose's signs and symptoms are the same as a bad air shock or strut, or valve body. Loss of ride height, especially at one corner or after sitting for an extended period, is the most common issue. The air compressor running more frequently is another common symptom as the pump works to keep the tank built up with an air supply. Just as with any other issue that results in uneven ride height, you'll probably see a chassis system failure fault if you have a bad or leaking air line.
Coil Spring Conversion
If, after all this, you decide you'd rather not have to deal with any potential or future problems, you can always install a Porsche Cayenne coil spring conversion kit from Arnott Industries. This kit will replace the air struts and shocks with standard custom-valved shocks and specially matched coil springs, and they come pre-assembled for ease-of-install. Arnott's kit also includes an Electronic Bypass Module (EBM) that keeps you from having any electronic fault codes that you would normally get from removing the air suspension. The only limitation is that this kit does not work on PDCC-equipped Cayennes.
Although it may seem as though the air suspension system of the 955 and 957 Porsche Cayenne is complex and potentially difficult to maintain, realize the majority of these problems are not common for every owner. While older and high mileage Cayenne problems will certainly pop up and need to be addressed, the majority of these will only need to be done once, and then you're good to go for another 100,000-200,000 miles. Investing in a good scan tool that can help you pinpoint and diagnose a problem when it arises can go a long way to making the maintenance and repair of the 955/957 Cayenne air suspension much easier.
If you're interested in more Porsche guides, DIYs, and technical articles, you can find them all at porsche.fcpeuro.com. If you're looking for 955/957 Cayenne specifically, you can find that here.
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