Porsche 959 Buyer's Guide

The Porsche 959’s hydraulic suspension system was one of the most technologically advanced features of any car in the 1980s, allowing adjustable ride height, adaptive damping, and a level of comfort unmatched in supercars of its time. However, while it was a groundbreaking innovation, it has also become one of the most expensive and failure-prone systems to maintain on the 959 today.

Unlike conventional suspension setups, the 959’s system used an advanced hydraulic network that controlled ride height and damping electronically. The driver could adjust the ride height via a switch in the cabin, allowing the car to be raised for rough roads or lowered for high-speed stability. This system was ahead of its time, but it relies on complex hydraulic actuators, pressure accumulators, and electronic solenoids, all of which are prone to leaks and failure over time.

Over the years, many 959 owners have experienced hydraulic suspension failures, often due to fluid leaks, pressure loss or electronic control module failure. The seals in the hydraulic struts degrade over time, leading to fluid leaks that result in sagging suspension. When there is pressure loss, the system uses hydraulic accumulators that can lose pressure, making the suspension unresponsive. The 959’s electronic ride height control system is another potential failure point, leading to stuck ride height settings or erratic performance. Sometimes, it can just get old. Since many 959s are driven infrequently, the hydraulic system can seize up, leading to expensive repairs.

When this system fails completely, the car can sink into a non-driveable state, making repairs urgent and costly. Fixing a Porsche 959’s hydraulic suspension system is an expensive undertaking, with a complete hydraulic suspension rebuild going to cost you over $50,000+ , plus you will need to replacement hydraulic struts (each corner) for around $8,000 per unit. The Electronic Suspension Control Unit is $10,000+ if replacement is needed. For many owners, the cost and difficulty of maintaining the hydraulic suspension have led them to seek alternative solutions.

Many Porsche 959 owners today opt to replace the hydraulic suspension with conventional coilover setups. This modification eliminates hydraulic fluid leaks, improves reliability and reduces long-term maintenance costs. Coilover conversions typically cost ~$15,000, making them far cheaper and more reliable than maintaining the original hydraulic system. While some purists prefer to keep the factory suspension, the conversion does not drastically impact value, as many collectors accept it as a practical upgrade.

If you're buying a Porsche 959, always check the service history of the hydraulic suspension. A 959 with a recently serviced or converted suspension system is significantly more reliable and less likely to require costly repairs. If you plan to keep the original system, be prepared for occasional failures and high repair costs—but for those who prioritize originality, it remains a key feature of the 959’s innovative design.

One of the Porsche 959’s most advanced and defining features is its sequential twin-turbocharged engine, which was a revolutionary innovation in the 1980s. Unlike traditional turbocharged engines of the era, which suffered from significant turbo lag, Porsche engineered the 959’s 2.85L flat-six with a sequential turbocharging system to deliver a progressive power curve and smoother acceleration. The system used two differently sized turbochargers—a smaller turbo for low-end response and a larger turbo that engaged at higher RPMs. This eliminated the sudden, violent boost surge common in older turbocharged cars and made the 959 one of the most controllable and usable supercars of its time.

However, while the turbo system was cutting-edge, it is also one of the most failure-prone and expensive components to maintain today. The turbos on the 959 are unique to the car—they were never shared with any other Porsche model, meaning replacements and rebuilds are costly and difficult to source.

Over time, 959 turbochargers degrade due to several factors. The 959’s high-performance engine generates extreme heat, which can lead to wear on the turbo bearings and seals. The turbos require precise lubrication, and if seals deteriorate, oil can leak into the intake or exhaust, causing smoke and performance loss. For the 959s that sit around too much, they can cause internal turbo components to seize or wear unevenly. Finally, the wastegates (which regulate boost pressure) can fail, leading to boost spikes or reduced power output. When 959 turbos start to fail, symptoms include excessive white or blue smoke from the exhaust or noticeable power loss or uneven acceleration or even inconsistent boost levels or delayed turbo response

If a Porsche 959’s turbochargers fail, repairs can be extremely expensive. A complete turbo replacement (pair) is probably at $30,000 – $40,000+ commitment. While a turbo rebuild is sometimes an option, that's still coming in around $15,000. The wastegate replacement seems cheap at $8,000 if that's the culprit. Since original turbochargers are no longer readily available, many owners choose to send the original turbos for professional rebuilding or to just upgrade to modern, more efficient turbo units (though this may impact originality and collector value).

The Porsche 959’s sequential turbo system was a game-changer, but turbo wear is inevitable, and replacement is one of the most expensive repairs on the car. If you're considering buying a 959, always check for recent turbo servicing, as neglected units can lead to a five-figure repair bill. For long-term ownership, regular driving, proper maintenance, and early inspections are key to keeping the 959’s legendary performance intact.

The Porsche 959 was one of the first supercars to feature an advanced digital engine management system, incorporating electronic fuel injection, turbo boost control, and all-wheel-drive integration. In an era when most supercars relied on mechanical fuel injection and analog systems, the 959’s Bosch Motronic engine control unit (ECU) was groundbreaking, allowing for precise fuel delivery, turbocharger sequencing, and real-time adjustments to power distribution. However, while this made the 959 incredibly sophisticated for its time, it also introduced long-term reliability concerns, particularly as the car ages.

Today, early digital engine management systems like the one in the Porsche 959 are notoriously difficult to diagnose and repair, especially since many of the control modules, sensors, and software are now outdated or difficult to source. Unlike modern Porsche ECUs, which can be plugged into diagnostic tools for quick troubleshooting, the 959’s engine management system requires specialized knowledge and equipment, often only available at Porsche Classic centers or expert restorers like Canepa.

If you’re considering a Porsche 959, pay close attention to ECU Functionality, and ensure the car’s engine management system is working properly with no fault codes. Ensure the car has had its recent electrical servicing. Cars that have had wiring or sensor updates are far less likely to have major issues. Check the engine management system controls the sequential turbo setup, so any boost inconsistencies or misfires could indicate electronic issues.

For long-term ownership, regular driving, software updates (if available), and proactive sensor replacements can help keep the 959’s complex electronics functioning properly. While its digital systems were groundbreaking for their time, they require specialized maintenance to avoid expensive failures in modern ownership.

The Porsche 959’s transmission was a masterpiece of engineering, featuring a six-speed manual gearbox paired with an advanced, electronically controlled all-wheel-drive system (PSK). At a time when most supercars still relied on simple rear-wheel-drive layouts and mechanical differentials, Porsche developed one of the most sophisticated drivetrain systems ever put into a road car. The PSK (Porsche-Steuer Kupplung) system could dynamically adjust power distribution between the front and rear wheels based on traction conditions, making the 959 incredibly stable and controllable, even in wet or slippery conditions. This level of innovation was decades ahead of its time, influencing modern Porsche 911 Turbo and Carrera 4 models.

However, while the 959’s transmission was an engineering triumph, it has also become one of the most complex and expensive components to maintain. Unlike the gearboxes in standard Porsches of the era, the 959’s transmission was a bespoke unit, meaning replacement parts are incredibly rare and costly. One of the main issues with the 959’s transmission is synchro wear, which can cause difficulty in shifting, gear grinding, or a notchy feel between gears. Since the 959’s gearbox was designed for durability at extreme speeds, rebuilding it requires precise machining and expertise, and few shops in the world are capable of servicing it properly. A complete transmission rebuild can cost between $50,000 and $80,000, making it one of the most expensive mechanical repairs on the car.

Another potential issue is related to the PSK all-wheel-drive system, which relies on a series of electronically controlled clutches and fluid-driven components. Over time, seals and hydraulic components can degrade, leading to fluid leaks or improper power distribution between the front and rear wheels. Since the PSK system was never used in any other Porsche, finding replacement parts or repairing damaged components can be a long and expensive process. Some owners who experience PSK failures opt to convert their 959 to a simpler rear-wheel-drive setup, but this significantly reduces originality and can negatively impact value.

For buyers considering a Porsche 959, it is essential to ensure that the transmission shifts smoothly, shows no signs of synchro wear, and has been serviced by a specialist familiar with the 959’s unique drivetrain. Regular fluid changes and preventive maintenance are crucial to preserving the gearbox, as neglected examples can quickly lead to five-figure repair bills. While the 959’s transmission is one of its most innovative and defining features, it is also one of the most expensive and difficult components to repair, requiring proper care, regular use, and expert servicing to keep it in optimal condition.

Owning a Porsche 959 comes with the challenge of sourcing parts that are both rare and incredibly expensive. Unlike mass-produced Porsche models, the 959 was built in extremely limited numbers—just 337 production cars—using many components that were never shared with any other vehicle. As a result, finding replacement parts for the 959 is far more difficult than for most classic Porsches, often requiring custom fabrication, lengthy wait times, and significant costs. While Porsche has made efforts through its Porsche Classic program to remanufacture select 959 components, many critical parts remain in short supply, making restoration and repairs a costly endeavor.

One of the most challenging aspects of 959 parts availability is its unique mechanical and electronic systems. The hydraulic suspension system, sequential twin-turbochargers, and all-wheel-drive PSK system were revolutionary for their time but were never carried over to other production Porsches. This means that when these components fail, finding replacement units or even sourcing rebuild kits can take months or even years. For example, a failing hydraulic suspension system may require a full overhaul that costs upwards of $50,000, while replacement 959-specific turbochargers can easily exceed $30,000 for a pair. Even relatively minor items, such as sensors, wiring harnesses, or ECU components, are difficult to find, as they were designed specifically for the 959’s advanced engine management system, which was decades ahead of its time.

Body and interior components present an equally significant challenge. Many 959 exterior panels were constructed using a blend of Kevlar, aluminum, and Nomex, which was groundbreaking in the 1980s but makes replacements difficult today. If a front or rear bumper is damaged, finding an OEM replacement can cost $20,000 or more, and in some cases, a specialist may need to custom-fabricate a new part from scratch. Even smaller trim pieces, such as interior switches, door handles, or dashboard components, are exceedingly rare, as Porsche only produced a limited number of these parts during the original manufacturing run.

For owners and potential buyers, understanding the difficulty of sourcing parts is critical to making an informed decision about Porsche 959 ownership. Some components can be found through Porsche Classic, specialist restoration shops like Canepa, or donor cars from previously wrecked 959s, but the costs and lead times can be prohibitive. Many owners opt to stockpile spare parts when they become available, as waiting until a critical failure occurs can leave the car sitting for months or even years while sourcing the necessary components. While the 959 remains one of the most legendary and collectible Porsche models, its limited parts availability is a significant consideration for long-term ownership, requiring careful planning, proactive maintenance, and access to specialized restoration resources.

When it comes to the Porsche 959, originality and proper documentation are critical to preserving its value and desirability in the collector car market. With only 337 production units built, the 959 is already an ultra-rare supercar, but the finest examples—the ones that command the highest prices—are those that have remained in original, factory-correct condition with complete service records. Any deviation from its factory specifications, whether through modifications, missing parts, or undocumented repairs, can significantly impact its long-term collectibility and resale value.

One of the most important aspects of originality in a Porsche 959 is the presence of matching-numbers components, including the engine, transmission, and body panels. Because the 959 was hand-assembled using a unique combination of materials, any replacement parts—especially those that are not OEM—can diminish the car’s historical significance. The use of non-original components, such as aftermarket turbochargers or coilover suspension conversions, may improve drivability and reliability, but they can also reduce the car’s appeal to purist collectors who seek a fully factory-correct example. Even seemingly minor modifications, like interior retrims or repaints in non-original colors, can detract from the car’s provenance and limit its investment potential.

Equally important is the provenance and documentation history of the car. A well-documented Porsche 959 should include its original purchase records, factory build sheets, service invoices, and any official maintenance or restoration reports. Because these cars were never officially imported into the United States when new, many early North American examples underwent Show and Display federalization, and verifying that these conversions were properly performed is crucial. Cars that were imported under questionable circumstances or have incomplete documentation may face significant hurdles when it comes to resale or registration.

For buyers looking to acquire a Porsche 959, thorough due diligence is essential. A car with a clean, documented history, full matching numbers, and original components will always command a premium over one with missing records or modifications. The rarest and most valuable examples are those that have been meticulously maintained, have minimal mileage, and include all original accessories such as factory toolkits, books, and keys. Ultimately, maintaining originality and keeping a detailed service history is not just about preserving authenticity—it is about ensuring that the Porsche 959 remains one of the most sought-after and appreciating collector cars in automotive history.