At a Glance
The Porsche 911 has 4 identified common problems across 8 generations, with the 996 (1998-2005) being the most affected generation and tyres & wheels the most common problem category. Based on 821K MOT tests from DVSA data.
Problems are patterns in the DVSA data that occur significantly more often on a specific model than the UK average — confirmed at 99% statistical confidence. Read our DVSA MOT data methodology →
Below: generation-by-generation comparison of Porsche 911 common problems, MOT failure types, and pass-rate data drawn from DVSA records. Click any generation to see fuel- and engine-specific fault patterns, mileage-banded repair guidance, and the most common MOT failures testers record.
MOT Tests & Failures by Generation
Porsche 911 generations by MOT tests, failures, and identified problems from DVSA data
Hover over each bar for a full breakdown. Tap any bar to view that generation's problems.
Showing total MOT tests, failures, and known problems per make. Hover over each bar for a full breakdown.
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Browse Porsche 911 Generations
Select a generation to see its specific problems, MOT failures and advisories
Original 901
G-Series 930
964
Top issue: Spark ignition emissions above threshold
993
Most common MOT failure: Tyre tread below 1.6mm limit
996
Top issue: Fuel cap damaged or missing
997
Most common MOT failure: Tyre condition
991
Most common MOT failure: Tyre condition
992
Most common MOT failure: Tyre condition
Most Common Porsche 911 MOT Failures
Every reason Porsche 911 vehicles fail their MOT, ranked by frequency. Select an individual year to see only that year’s failures, or stay on ‘All time’ for the combined picture across our 20 years of DVSA data. Scroll inside the table for the full list.
| # | Failure | % of failures |
|---|---|---|
| 1 | Tyre tread depth below limit | 10.26% |
| 2 | Tyre condition | 7.41% |
| 3 | Number plate lamp not working | 5.83% |
| 4 | Windscreen washer not working | 4.72% |
| 5 | Brake hydraulic component worn | 4.31% |
| 6 | Front lamp not working | 4.25% |
| 7 | Wiper blades deteriorated | 4.06% |
| 8 | Brake performance below minimum | 4.01% |
| 9 | Headlamp aim defect | 3.92% |
| 10 | Stop lamp not working | 3.48% |
| 11 | Brake disc or drum worn | 3.36% |
| 12 | Suspension joint or bush worn | 3.32% |
| 13 | Driveshaft fault | 3.12% |
| 14 | Fog lamp not working | 2.69% |
| 15 | Spark ignition emissions above threshold | 2.68% |
| 16 | Indicator fault | 2.64% |
| 17 | Catalytic converter efficiency low | 2.30% |
| 18 | Rigid brake pipe corroded or damaged | 2.09% |
| 19 | Position lamp not working | 2.04% |
| 20 | Exhaust system fault | 1.62% |
| 21 | Headlamp fault | 1.51% |
| 22 | Track rod end worn | 1.33% |
| 23 | Shock absorber worn or leaking | 1.15% |
| 24 | Horn not working | 1.12% |
| 25 | Rear lamp not working | 1.11% |
| 26 | Rear fog lamp not working | 0.98% |
| 27 | Ball joint dust cover split | 0.93% |
| 28 | Coil spring broken or corroded | 0.87% |
| 29 | Steering rack fault | 0.87% |
| 30 | Windscreen damage affecting view | 0.84% |
| 31 | Parking brake performance below minimum | 0.69% |
| 32 | Exhaust emissions above threshold (non-catalyst) | 0.67% |
| 33 | Brake pads or linings worn | 0.59% |
| 34 | Suspension mounting corroded | 0.57% |
| 35 | ABS fault | 0.56% |
| 36 | Airbag warning light on | 0.54% |
| 37 | Dashboard warning lamp fault | 0.47% |
| 38 | Fuel cap damaged or missing | 0.45% |
| 39 | Front suspension fault | 0.39% |
| 40 | Seat belt condition | 0.26% |
| 41 | Battery loose or leaking | 0.26% |
| 42 | Headlamp levelling device fault | 0.22% |
| 43 | Front suspension joint worn | 0.22% |
| 44 | Flexible brake hose damaged | 0.22% |
| 45 | Tyre valve stem damaged | 0.21% |
| 46 | Brake pedal movement restricted | 0.20% |
| 47 | Mirror damaged or missing | 0.19% |
| 48 | Electrical switch fault | 0.19% |
| 49 | Chassis condition | 0.18% |
| 50 | Parking brake condition | 0.18% |
| 51 | MacPherson strut worn | 0.18% |
| 52 | Brake caliper fault | 0.17% |
| 53 | Brake fluid leak | 0.16% |
| 54 | Body corrosion or damage | 0.16% |
| 55 | Suspension linkage fault | 0.16% |
| 56 | Engine oil leak | 0.16% |
| 57 | Steering column fault | 0.15% |
| 58 | Rear suspension fault | 0.14% |
| 59 | Power steering pipe or hose leaking | 0.14% |
| 60 | Brake pedal fault | 0.14% |
| 61 | Tyre pressure monitoring system fault | 0.13% |
| 62 | Headlamp washer not working | 0.11% |
| 63 | Wheel bearing worn | 0.11% |
| 64 | Electronic stability control fault | 0.09% |
| 65 | Tyre size or type not matched | 0.09% |
| 66 | Steering arm worn | 0.08% |
| 67 | Steering operation fault | 0.07% |
| 68 | Electrical wiring fault | 0.07% |
| 69 | Bonnet catch or hinge fault | 0.07% |
| 70 | Steering lock fault | 0.07% |
| 71 | Rear fog lamp warning light fault | 0.05% |
| 72 | Anti-roll bar worn or corroded | 0.05% |
| 73 | Steering wheel damaged or insecure | 0.05% |
| 74 | Subframe mounting corroded | 0.05% |
| 75 | Front passenger door fault | 0.05% |
| 76 | Propshaft fault | 0.05% |
| 77 | Suspension arm worn or corroded | 0.05% |
| 78 | Brake fluid warning light on | 0.05% |
| 79 | Passenger seat fault | 0.05% |
| 80 | Brake fluid level low or contaminated | 0.05% |
| 81 | Driver airbag fault | 0.04% |
| 82 | Driver door fault | 0.04% |
| 83 | Compression ignition emissions above threshold | 0.04% |
| 84 | Driver seat fault | 0.04% |
| 85 | Steering free play excessive | 0.04% |
| 86 | Brake lever fault | 0.04% |
| 87 | Dip switch fault | 0.04% |
| 88 | Vehicle structure corrosion | 0.04% |
| 89 | Exhaust leak | 0.04% |
| 90 | Fuel pipe corroded or damaged | 0.03% |
| 91 | Fuel tank corroded or leaking | 0.03% |
| 92 | Rear reflector damaged or missing | 0.03% |
| 93 | Brake back plate corroded or damaged | 0.03% |
| 94 | Fuel hose damaged or leaking | 0.03% |
| 95 | Handbrake cable fault | 0.03% |
| 96 | Boot lid damaged or insecure | 0.03% |
| 97 | Brake servo fault | 0.02% |
| 98 | Handbrake lever fault | 0.02% |
| 99 | Power steering ram fault | 0.02% |
| 100 | Bonded suspension condition | 0.02% |
| 101 | Speedometer fault | 0.02% |
| 102 | Transmission oil leak | 0.02% |
| 103 | Drag link end worn | 0.01% |
| 104 | Hydraulic brake cylinder fault | 0.01% |
| 105 | Electronic parking brake fault | 0.01% |
| 106 | Brake cable, rod, lever or linkage fault | 0.01% |
| 107 | Brake air or vacuum system fault | <0.01% |
| 108 | Hydraulic fluid leak | <0.01% |
| 109 | Suspension unit fault | <0.01% |
| 110 | Spring mounting corroded | <0.01% |
| 111 | Undertray damaged or missing | <0.01% |
| 112 | Main beam warning light fault | <0.01% |
| 113 | Body security fault | <0.01% |
| 114 | Bumper damaged or insecure | <0.01% |
| 115 | Tie bar or rod worn or corroded | <0.01% |
| 116 | Engine mounting worn or broken | <0.01% |
| 117 | Torsion bar worn or corroded | <0.01% |
| 118 | Subframe corrosion or damage | <0.01% |
| 119 | Suspension retaining or locking device fault | <0.01% |
| 120 | Additional braking device fault | <0.01% |
| 121 | Trailing arm worn or corroded | <0.01% |
| 122 | Electric power steering fault | <0.01% |
| 123 | Reversing lamp not working | <0.01% |
| 124 | Suspension linkage attachment bracket or mounting corroded | <0.01% |
| 125 | Semaphore indicator fault | <0.01% |
| 126 | Steering coupling worn | <0.01% |
| 127 | Brake fluid reservoir fault | <0.01% |
| 128 | Suspension rod worn or corroded | <0.01% |
| 129 | Full power hydraulic brake fault | <0.01% |
| 130 | Indicator warning light fault | <0.01% |
| 131 | Brake master cylinder or servo mounting fault | <0.01% |
| 132 | Brake pressure or vacuum buildup insufficient | <0.01% |
| 133 | Window damaged or won't operate | <0.01% |
| 134 | Access panel damaged or insecure | <0.01% |
| 135 | Brake master cylinder fault | <0.01% |
| 136 | Brake valve fault | <0.01% |
| 137 | Passenger airbag fault | <0.01% |
| 138 | Radius arm worn or corroded | <0.01% |
| 139 | Steering shaft fault | <0.01% |
| 140 | Torque or reaction arm worn | <0.01% |
| 141 | Brake linkage mounting fault | <0.01% |
| 142 | Exhaust heat shield or sound insulation damaged | <0.01% |
| 143 | Vehicle floor corroded | <0.01% |
| 144 | Body strengthening plate corroded | <0.01% |
| 145 | CV joint worn | <0.01% |
| 146 | Electronic braking system fault | <0.01% |
| 147 | Seat belt anchorage fault | <0.01% |
| 148 | Handbrake mechanism or mounting fault | <0.01% |
| 149 | Mirror or camera fault | <0.01% |
| 150 | Outline marker lamp not working | <0.01% |
| 151 | Power steering pump fault | <0.01% |
| 152 | Steering box fault | <0.01% |
| 153 | Tailgate damaged or insecure | <0.01% |
| 154 | King pin or swivel pin worn | <0.01% |
| 155 | Air suspension levelling valve fault | <0.01% |
| 156 | Front fog lamp not working | <0.01% |
| 157 | Transmission drive belt fault | <0.01% |
| 158 | Brake pedal linkage fault | <0.01% |
| 159 | Spare wheel fault | <0.01% |
| 160 | Wheel hub fault | <0.01% |
| 161 | Brake clevis joint worn | <0.01% |
| 162 | Halfshaft fault | <0.01% |
| 163 | Handbrake fails on gradient | <0.01% |
| 164 | Hydraulic suspension accumulator fault | <0.01% |
| 165 | Passenger compartment corrosion | <0.01% |
| 166 | Seat belt or padding damaged | <0.01% |
| 167 | Steering damper fault | <0.01% |
| 168 | Steering lock stop fault | <0.01% |
| 169 | Universal joint worn | <0.01% |
| 170 | Brake slack adjuster fault | <0.01% |
| 171 | Brake wheel cylinder fault | <0.01% |
| 172 | Hand-operated brake valve condition | <0.01% |
| 173 | Hazard warning light fault | <0.01% |
| 174 | Loading door damaged or insecure | <0.01% |
| 175 | Seat belt pre-tensioner fault | <0.01% |
| 176 | Suspension coupling worn | <0.01% |
| 177 | Towbar fault | <0.01% |
Showing all 177 reasons — scroll inside the table for the full list.
Porsche 911 MOT Failures by Category
Total MOT failure occurrences for the Porsche 911, grouped by category. Same data as the failures table above — just sliced by category instead of fault title. Hover a slice for the top failures in each category.
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Frequently Asked Questions
What are the most common Porsche 911 problems?
Based on analysis of 821K Porsche 911 MOT tests from DVSA data, we have 4 identified common problems across 8 generations. The most frequently flagged issue is "Fuel cap damaged or missing". Tyres & Wheels is the most common problem category.
Which Porsche 911 generation has the most problems?
The Porsche 911 996 (1998-2005) (1998–2005) has the highest number of identified common problems (3). Click the generation card above for the full breakdown.
How is this data calculated?
We analyse anonymised DVSA MOT test records under the Open Government Licence. An issue is classified as a "Common Problem" when it occurs significantly more often on a specific model than the UK average, confirmed at 99% statistical confidence. Read the full methodology page for details.
Can I report a problem with my Porsche 911?
Yes — use the "Tell Us About Your Problem" form on this page. Your report helps other Porsche 911 owners spot problems early. All submissions are reviewed before being added to the public database.
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