Porsche · Known Issues
2018 Porsche 911 Problems: 10 Known Issues
2018 model year · 12,500+ owner reports · Updated September 2026
2018 · All trims · All engines
Choose the year and equipment for your written issues and visual request.
2018 model year · 12,500+ owner reports · Updated September 2026
2018 · All trims · All engines
Choose the year and equipment for your written issues and visual request.
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According to Au7o's analysis of 12,500+ owner reports, the 2018 Porsche 911 has 10 documented known issues, with 4 rated critical. The most serious are 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) and 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). The most commonly reported issue is Rear Main Seal (RMS) Oil Leak with 3,800 owner reports. Across all issues with published estimates, repair costs range from $150 to $25,000. DIY maintenance guides at au7o.io.
AIR BAGS: AIR BAG/RESTRAINT CONTROL MODULE
Porsche Cars North America, Inc. (Porsche) is recalling certain 2016-2017 911 and Boxster, 2016 Cayman and Panamera vehicles. The air bag Electronic Control Unit (ECU) may have a defective power supply capacitor that can result in air bag deactivation or inadvertent deployment of the air bags.
AIR BAGS:SIDE/WINDOW
Porsche Cars North America, Inc. (Porsche) is recalling certain model year 2017 718 Boxster, 718 Boxster S, 718 Cayman, 718 Cayman S, 911 Carrera, 911 Carrera S, 911 Carrera S Cabriolet, 911 Carrera 4S, 911 Turbo, 911 Turbo S, 911 Carrera 4S Cabriolet, and 911 Turbo Cabriolet vehicles. The seat mounted side air bag inflator initiator may fail to ignite during a crash.
AIR BAGS
Porsche Cars North America, Inc. (Porsche) is recalling certain 2018 718 Boxster, Boxster S and Boxster GTS, 718 Cayman, Cayman S and Cayman GTS, 911 Carrera, Carrera T, Targa 4 GTS, Carrera 4, Carrera S, Carrera 4S, Carrera GTS, Carrera 4 GTS, Carrera Cabriolet, Carrera S Cabriolet, Carrera 4S Cabriolet, Carrera GTS Cabriolet, Carrera 4 GTS Cabriolet, Targa 4, Targa 4S, Turbo, Turbo S, Turbo S Exclusive Series, Turbo Cabriolet, Turbo S Cabriolet and GT3 vehicles. The side air bag impact sensors may not have been properly tightened to the vehicle.
VISIBILITY:WINDSHIELD
Porsche Cars North America, Inc. (Porsche) is recalling certain 2017 911 Carrera Cabriolet, 911 Carrera 4 Cabriolet, 911 Carrera 4S Cabriolet, 911 Carrera S Cabriolet, 911 Targa S, 911 Targa 4S, 911 Turbo Cabriolet, 718 Boxter and 718 Boxter S vehicles. During manufacturing, the windshield may not have been properly bonded to the vehicle, allowing it to detach in a crash. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 212, "Windshield Mounting."
AIR BAGS:FRONTAL:PASSENGER SIDE:INFLATOR MODULE
Porsche Cars North America, Inc. (Porsche) is recalling certain 2016 911 GT3 RS and 911 R vehicles and 2017 911 Carrera, 911 Carrera Cabriolet, 911 Carrera 4, 911 Carrera 4S, 911 Carrera 4S Cabriolet, 911 Carrera S, 911 Carrera S Cabriolet, 911 Targa 4, 911 Targa 4S, 911 Turbo S, 911 Turbo S Cabriolet, 718 Boxster, 718 Boxster S, 718 Cayman and 718 Cayman S vehicles. The passenger frontal air bag inflator initiator may fail to ignite during a crash.
+ 2 more recalls. Check all on NHTSA.gov
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According to Au7o's analysis of 12,500+ owner reports, the 2018 Porsche 911 has 10 documented issues. The most frequently reported are: Cylinder Bore Scoring (Nikasil Wear), Timing Chain Tensioner and Guide Failure, Coolant Pipe and Fitting Leaks. Of these, 4 are rated critical and should be addressed promptly.
The 2018 Porsche 911 has 10 known issues documented across 12,500+ owner reports. 4 issues are rated critical: 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). 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.
Repair costs for known Porsche 911 issues range from $150 to $25,000, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Cylinder Bore Scoring (Nikasil Wear), typically costs $8,000-$25,000 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
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.
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.
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.
Porsche extended the warranty on the coolant pump (Part ID 1950) and the valve block (Part ID 2423) to ten years from delivery or 120,000 miles for USA, Canada and Puerto Rico cars, specifically on the 991.2 Carrera family built for model years 2017-2018 with the 3.0-litre twin-t… Repairs typically run $1,800-$3,500. Severity: high.
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.
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.
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.
Porsche symptom-based bulletin SY 72/17 (Group 8, 8530) covers the 911 (991) line from model year 2012 through 2021, which includes the entire 991.2 run. The complaint is that the fresh-air fan for the heating/ventilation system simply does not run - no blower on any speed, so no… Repairs typically run $150-$900. Severity: medium.
Porsche symptom-based bulletin SY 130/19 (Group 3, 3734) applies to the 911 GT3 (991) and 911 GT3 RS (991) for model years 2014 through 2019, which includes the 991.2 GT3 and GT3 RS with the 4.0-litre naturally aspirated flat-six and PDK. The symptom is transmission oil leaking o… Repairs typically run $1,200-$3,200. Severity: medium.
Porsche Advanced Technical Information bulletin 2106.1, later reissued as symptom-based bulletin SY 109/21 (Group 4, 4407), covers 911 (991) cars fitted with the central wheel lock (M-no. 478): Carrera GTS, Turbo, Turbo S, GT3, GT3 RS, GT2 RS and Speedster, model years 2014 throu… Repairs typically run $300-$2,500. Severity: low.
Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.