What is the 1999-2008 Porsche 911 Intermediate Shaft (IMS) Bearing Failure?

The IMS bearing on 996 and early 997 flat-six engines is a single-row or dual-row sealed bearing that loses lubrication over time, leading to catastrophic bearing failure and engine destruction. The dual-row bearing (1999-2005) fails less frequently than the single-row (2006-2008… Repairs typically run $2,000-$4,500. Severity: high.

What is the 2009-2019 Porsche 911 Cylinder Bore Scoring (Nikasil Wear)?

The 991-generation 911 suffers from cylinder bore scoring where the Lokasil cylinder liners develop deep vertical scores, typically on cylinders 1 and 6. This is caused by inadequate oil supply to the cylinder walls during cold starts and short-trip driving. The issue results in… Repairs typically run $8,000-$25,000. Severity: high.

What is the 2009-2019 Porsche 911 Timing Chain Tensioner and Guide Failure?

The 991-generation timing chain tensioners can lose hydraulic pressure, particularly after the car has been sitting for extended periods. This allows chain slack on startup, which can jump timing and cause catastrophic valve-to-piston contact. The plastic chain guides also wear p… Repairs typically run $3,000-$7,000. Severity: high.

What is the 2012-2019 Porsche 911 Coolant Pipe and Fitting Leaks?

The plastic coolant pipes and quick-connect fittings on the 991 generation are prone to cracking and leaking, especially at the connections near the front radiators. The plastic becomes brittle with heat cycling and age. Coolant loss can be gradual and difficult to detect until t… Repairs typically run $800-$2,500. Severity: high.

What is the 2020-2024 Porsche 911 Windshield and Rear Window Bonding Failure (Recall 24V-155 / ARA3)?

Porsche's Part 573 report for recall 24V-155 states that on affected 992-generation 911s "the front and rear windows were not manufactured in accordance with the specifications and therefore not bonded sufficiently to the body." The root cause was a supplier cleaning-process erro… Repairs typically run $0-$0. Severity: high.

What is the 1965-1975 Porsche 911 Structural rust in kidney bowls, longitudinals, floor pan and battery box?

Pre-1976 911 bodies were NOT galvanized, and the unibody is full of closed box sections that trap moisture. The classic rot spots are the kidney bowls (where the rear torsion-bar tube/longitudinal meets the inner sill — a critical structural junction), the longitudinals (rocker b… Repairs typically run $3,000-$30,000. Severity: high.

What is the 1965-1983 Porsche 911 Timing chain tensioner collapse on pre-1984 cars destroys the engine?

Every 911 built through 1983 uses spring-loaded mechanical cam chain tensioners that lose their hydraulic damping oil and collapse with age and heat cycling. When a tensioner fails the slack timing chain jumps a tooth (or off the sprocket entirely), the cams lose sync with the cr… Repairs typically run $700-$1,800. Severity: high.

What is the 1999-2019 Porsche 911 Rear Main Seal (RMS) Oil Leak?

The rear main seal on the M96, M97, and MA1 flat-six engines is prone to leaking oil onto the clutch and flywheel. The seal hardens over time and the flange design allows oil to migrate past the seal. This is often discovered during clutch replacement or when oil drips appear und… Repairs typically run $1,500-$3,500. Severity: medium.

What is the 1999-2008 Porsche 911 Air-Oil Separator (AOS) Failure?

The AOS diaphragm on M96/M97 engines ruptures over time, causing unmetered air leaks into the intake manifold and excessive oil consumption. The failed AOS allows oil vapor to be drawn directly into the intake system rather than being separated and returned to the crankcase. This… Repairs typically run $500-$1,500. Severity: medium.

What is the 2009-2019 Porsche 911 Direct Injection Intake Valve Carbon Buildup?

The direct injection system on 991 engines does not spray fuel over the intake valves, allowing carbon deposits to accumulate on the valve stems and ports. Over time this restricts airflow, causing rough idle, misfires, and reduced power. The flat-six layout makes walnut blasting… Repairs typically run $800-$1,800. Severity: medium.

What is the 2025-2026 Porsche 911 "Rear Axle Steering Failed" Warning from Right Servo Motor Fault Codes?

Porsche Technical Information 07/25 ENU 4883 applies to the 911 Carrera GTS (992), 911 Carrera 4 GTS (992), 911 Turbo (992) and 911 Turbo S (992) from model year 2025 equipped with rear axle steering (M-no. 0N5). The customer complaint is that "the yellow warning message 'Rear ax… Repairs typically run $0-$300. Severity: medium.

What is the 2021-2022 Porsche 911 GT3 4.0L Oil Tank Threaded Insert Separates When the Drain Plug Is Loosened?

Porsche Technical Information 96/22 ENU 1752 applies specifically to the 911 GT3 (992) and 911 GT3 with Touring Package (992), model years 2021 through 2022. On cars built before 27 January 2022 (engine number DRM 004177), "it is possible for the threaded insert, into which the o… Repairs typically run $150-$3,500. Severity: medium.

What is the 2020 Porsche 911 Coolant Pump Mechanical Seal Leak - Workshop Campaign WKJ7?

Porsche Technical Information 137/19 ENU WKJ7 opens a workshop campaign on model year 2020 911 (992) cars, stating that "during internal tests, Porsche has discovered that leaks can occur at the mechanical seal of the coolant pump over the service life of the vehicle. Coolant wil… Repairs typically run $0-$2,600. Severity: medium.

What is the 2022-2023 Porsche 911 PCM Central Computer Software 37xx - Black Screen, Audio and Navigation Failures?

Porsche Technical Information 65/23 ENU 9152 covers 911 (992) model years 2022 through 2023 running central computer (PCM) software version 37xx. Porsche describes the condition as "the PCM cannot be switched on, fails intermittently during vehicle operation or starts up again in… Repairs typically run $0-$400. Severity: medium.

What is the 2025 Porsche 911 Low-Beam Headlight Glare from Front-End Electronics Control Module Software Error (Recall 25V-079)?

NHTSA recall 25V-079 covers 2025 Porsche 911s among other Porsche models. Porsche states that "a software error in the front-end electronics control module may result in the low beam headlights creating a glare for oncoming traffic," and that "excessive glare can decrease the vis… Repairs typically run $0-$0. Severity: medium.

What is the 2017-2018 Porsche 911 Airbag Warning Light From Corrosion in the Unused Key-Switch Connector Behind the Glovebox?

Porsche Advanced Technical Information bulletin 1801 (Group 6, Part ID 6953) covers the 911 (991) Gen. II and 718 Boxster/Cayman (982) for model years 2017-2018. The driver gets an airbag warning in the instrument cluster and the workshop finds fault code 002502 'Key-operated swi… Repairs typically run $150-$600. Severity: medium.

What is the 2021-2022 Porsche 911 PASM "Chassis System Fault" from Body Acceleration Sensor Initialization Error?

Porsche Technical Information 213/21 ENU 4316 applies to the 911 (992) for model years 2021 through 2022. The yellow warning message "Chassis system fault" is displayed in the instrument cluster and one or more of the following entries are stored in the PASM control unit: C10B804… Repairs typically run $0-$350. Severity: medium.

Porsche · Known Issues

1965-2026 Porsche 911 Problems: 31 Known Issues

1965-2026 model years · 20,800+ owner reports · Updated August 2026

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According to Au7o's analysis of 20,800+ owner reports, the 1965-2026 Porsche 911 has 31 documented known issues, with 10 rated critical. The most serious are Intermediate Shaft (IMS) Bearing Failure ($2,000-$4,500 repair), Cylinder Bore Scoring (Nikasil Wear) ($8,000-$25,000 repair), Timing Chain Tensioner and Guide Failure ($3,000-$7,000 repair), Coolant Pipe and Fitting Leaks ($800-$2,500 repair), Coolant Pump and Vacuum Valve Block Failure on 3.0L Twin-Turbo (Warranty Extended to 10 Years / 120,000 Miles) ($1,800-$3,500 repair), Windshield and Rear Window Bonding Failure (Recall 24V-155 / ARA3) ($0-$0 repair), Dashboard Console Breakage Compromising Passenger Airbag Deployment (Recall 22V-897 / ANB7) ($0-$0 repair), Center-Lock Wheel Bolt Fracture on Center-Lock-Equipped 992 Models (Recall 24V-809 / ARC4) ($0-$0 repair), Structural rust in kidney bowls, longitudinals, floor pan and battery box. at .

Frequently Asked Questions

What are the most common Porsche 911 problems?

According to Au7o's analysis of 20,800+ owner reports, the 1965-2026 Porsche 911 has 31 documented issues. The most frequently reported are: Intermediate Shaft (IMS) Bearing Failure, Cylinder Bore Scoring (Nikasil Wear), Timing Chain Tensioner and Guide Failure. Of these, 10 are rated critical and should be addressed promptly.

Is the Porsche 911 reliable?

The 1965-2026 Porsche 911 has 31 known issues documented across 20,800+ owner reports. 10 issues are rated critical: Intermediate Shaft (IMS) Bearing Failure and Cylinder Bore Scoring (Nikasil Wear) and Timing Chain Tensioner and Guide Failure and Coolant Pipe and Fitting Leaks and Coolant Pump and Vacuum Valve Block Failure on 3.0L Twin-Turbo (Warranty Extended to 10 Years / 120,000 Miles) and Windshield and Rear Window Bonding Failure (Recall 24V-155 / ARA3) and Dashboard Console Breakage Compromising Passenger Airbag Deployment (Recall 22V-897 / ANB7) and Center-Lock Wheel Bolt Fracture on Center-Lock-Equipped 992 Models (Recall 24V-809 / ARC4) and Structural rust in kidney bowls, longitudinals, floor pan and battery box and Timing chain tensioner collapse on pre-1984 cars destroys the engine. Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common Porsche 911 problems?

Repair costs for known Porsche 911 issues range from $0 to $30,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Intermediate Shaft (IMS) Bearing Failure, typically costs $2,000-$4,500 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What year Porsche 911 is the most reliable?

Reliability varies across model years of the Porsche 911. Based on documented issues, problems are most commonly reported in earlier model years. Au7o recommends checking the specific known issues for your target year before purchasing, and having a pre-purchase inspection performed by a qualified mechanic. Our known issues database covers the 1965-2026 Porsche 911 with 31 documented issues documented across 20,800+ owner reports.

All 31 Known Issues

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Frequently Asked Questions

What are the most common Porsche 911 problems?

Is the Porsche 911 reliable?

How much does it cost to fix common Porsche 911 problems?

What year Porsche 911 is the most reliable?

When Issues Typically Appear

Intermediate Shaft (IMS) Bearing Failure#

Cylinder Bore Scoring (Nikasil Wear)#

Timing Chain Tensioner and Guide Failure#

Timing chain tensioner collapse on pre-1984 cars destroys the engine#

Rear Main Seal (RMS) Oil Leak#

Air-Oil Separator (AOS) Failure#

Direct Injection Intake Valve Carbon Buildup#

GT3 4.0L Oil Tank Threaded Insert Separates When the Drain Plug Is Loosened#

Chronic oil leaks from cooler lines, thermostat seal and chain housings#

Upper Oil Pan Seal Housing Leak from Injection-Molding Flash#

Coolant Pipe and Fitting Leaks#

Coolant Pump and Vacuum Valve Block Failure on 3.0L Twin-Turbo (Warranty Extended to 10 Years / 120,000 Miles)#

Coolant Pump Mechanical Seal Leak - Workshop Campaign WKJ7#

Windshield and Rear Window Bonding Failure (Recall 24V-155 / ARA3)#

Structural rust in kidney bowls, longitudinals, floor pan and battery box#

Center-Lock Wheel Bolt Fracture on Center-Lock-Equipped 992 Models (Recall 24V-809 / ARC4)#

PASM "Chassis System Fault" from Body Acceleration Sensor Initialization Error#

Front-Axle Lift "Lift System Fault - Service Necessary" and Height Measurement Error#

Dashboard Console Breakage Compromising Passenger Airbag Deployment (Recall 22V-897 / ANB7)#

Airbag Warning Light From Corrosion in the Unused Key-Switch Connector Behind the Glovebox#

PCM Central Computer Software 37xx - Black Screen, Audio and Navigation Failures#

Low-Beam Headlight Glare from Front-End Electronics Control Module Software Error (Recall 25V-079)#

12V Lithium-Ion Lightweight Battery Component Protection De-Energizes the Car and Is Misdiagnosed as a Dead Battery#

Connect Control Unit Drains the 12V Battery Flat in Three to Four Days (PVTS Alarm Loop)#

8-Speed PDK Transmission Oil Leaks#

915 gearbox worn 2nd-gear synchros and rounded dog teeth#

PDK Transmission Oil Leaks From the Clutch-Chamber Vent Line During Track Driving#

"Rear Axle Steering Failed" Warning from Right Servo Motor Fault Codes#

CIS airbox blows apart from an intake backfire#

Fresh-Air Blower Motor Seizes After the Car Sits - No Heat, Vent or Defroster#