At a Glance
The Triumph Stag has 40 identified common problems across 1 generation, with the Stag (1970-1977) being the most affected generation and suspension the most common problem category. Based on 72K 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 Triumph Stag 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
Triumph Stag 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 Triumph Stag Generations
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Most Common Triumph Stag MOT Failures
Every reason Triumph Stag 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 | Brake performance below minimum | 8.30% |
| 2 | Number plate lamp not working | 7.23% |
| 3 | Exhaust system fault | 5.77% |
| 4 | Suspension joint or bush worn | 5.17% |
| 5 | Front lamp not working | 4.07% |
| 6 | Body corrosion or damage | 3.89% |
| 7 | Indicator fault | 3.82% |
| 8 | Front suspension joint worn | 3.58% |
| 9 | Tyre condition | 3.51% |
| 10 | Windscreen washer not working | 3.37% |
| 11 | Headlamp aim defect | 3.26% |
| 12 | Tyre tread depth below limit | 3.02% |
| 13 | Stop lamp not working | 2.76% |
| 14 | Wiper blades deteriorated | 2.43% |
| 15 | Suspension mounting corroded | 1.98% |
| 16 | Parking brake performance below minimum | 1.67% |
| 17 | Parking brake condition | 1.62% |
| 18 | Position lamp not working | 1.53% |
| 19 | Track rod end worn | 1.49% |
| 20 | Brake hydraulic component worn | 1.49% |
| 21 | Chassis condition | 1.36% |
| 22 | Steering rack fault | 1.32% |
| 23 | Rear lamp not working | 1.30% |
| 24 | Driveshaft fault | 1.10% |
| 25 | Spring mounting corroded | 0.98% |
| 26 | Steering free play excessive | 0.96% |
| 27 | Front suspension fault | 0.95% |
| 28 | Handbrake cable fault | 0.92% |
| 29 | Horn not working | 0.90% |
| 30 | Seat belt condition | 0.87% |
| 31 | Wheel bearing worn | 0.85% |
| 32 | Ball joint dust cover split | 0.82% |
| 33 | Brake disc or drum worn | 0.82% |
| 34 | Subframe mounting corroded | 0.81% |
| 35 | Brake pads or linings worn | 0.78% |
| 36 | Battery loose or leaking | 0.72% |
| 37 | Rear suspension fault | 0.68% |
| 38 | Brake pedal fault | 0.59% |
| 39 | Exhaust emissions above threshold (non-catalyst) | 0.58% |
| 40 | Shock absorber worn or leaking | 0.57% |
| 41 | Suspension linkage fault | 0.56% |
| 42 | Steering column fault | 0.55% |
| 43 | Tyre size or type not matched | 0.55% |
| 44 | Headlamp fault | 0.45% |
| 45 | Vehicle structure corrosion | 0.43% |
| 46 | MacPherson strut worn | 0.41% |
| 47 | Steering lock fault | 0.35% |
| 48 | Steering wheel damaged or insecure | 0.35% |
| 49 | Windscreen damage affecting view | 0.35% |
| 50 | Fuel cap damaged or missing | 0.34% |
| 51 | Rigid brake pipe corroded or damaged | 0.31% |
| 52 | Power steering pump fault | 0.30% |
| 53 | Brake caliper fault | 0.29% |
| 54 | Brake pedal movement restricted | 0.29% |
| 55 | Electrical wiring fault | 0.28% |
| 56 | Engine oil leak | 0.27% |
| 57 | Power steering pipe or hose leaking | 0.25% |
| 58 | Brake wheel cylinder fault | 0.24% |
| 59 | Electrical switch fault | 0.22% |
| 60 | Brake lever fault | 0.21% |
| 61 | Coil spring broken or corroded | 0.21% |
| 62 | Fuel pipe corroded or damaged | 0.20% |
| 63 | Spark ignition emissions above threshold | 0.20% |
| 64 | Brake fluid leak | 0.20% |
| 65 | Flexible brake hose damaged | 0.20% |
| 66 | Fuel tank corroded or leaking | 0.17% |
| 67 | Drag link end worn | 0.17% |
| 68 | Steering operation fault | 0.17% |
| 69 | Mirror damaged or missing | 0.16% |
| 70 | Suspension retaining or locking device fault | 0.16% |
| 71 | Suspension arm worn or corroded | 0.16% |
| 72 | Fuel hose damaged or leaking | 0.15% |
| 73 | Steering shaft fault | 0.15% |
| 74 | Brake air or vacuum system fault | 0.12% |
| 75 | Brake clevis joint worn | 0.12% |
| 76 | Bonded suspension condition | 0.12% |
| 77 | Steering coupling worn | 0.11% |
| 78 | Brake cable, rod, lever or linkage fault | 0.10% |
| 79 | Steering arm worn | 0.10% |
| 80 | Transmission oil leak | 0.10% |
| 81 | Power steering ram fault | 0.09% |
| 82 | Steering drive system fault | 0.09% |
| 83 | Bonnet catch or hinge fault | 0.08% |
| 84 | Tyre valve stem damaged | 0.08% |
| 85 | Fog lamp not working | 0.08% |
| 86 | Driver seat fault | 0.07% |
| 87 | Passenger seat fault | 0.07% |
| 88 | Speedometer fault | 0.07% |
| 89 | Brake fluid reservoir fault | 0.06% |
| 90 | Front passenger door fault | 0.06% |
| 91 | Subframe corrosion or damage | 0.06% |
| 92 | Universal joint worn | 0.06% |
| 93 | Boot lid damaged or insecure | 0.06% |
| 94 | Body security fault | 0.05% |
| 95 | Brake fluid level low or contaminated | 0.05% |
| 96 | Tie bar or rod worn or corroded | 0.05% |
| 97 | Dashboard warning lamp fault | 0.05% |
| 98 | Dip switch fault | 0.05% |
| 99 | Vehicle floor corroded | 0.04% |
| 100 | Exhaust leak | 0.04% |
| 101 | Handbrake lever fault | 0.04% |
| 102 | Hydraulic brake cylinder fault | 0.04% |
| 103 | Brake relay lever fault | 0.03% |
| 104 | Anti-roll bar worn or corroded | 0.03% |
| 105 | Brake fluid warning light on | 0.03% |
| 106 | Driver door fault | 0.03% |
| 107 | Handbrake mechanism or mounting fault | 0.03% |
| 108 | Hydraulic fluid leak | 0.03% |
| 109 | Rear reflector damaged or missing | 0.03% |
| 110 | Steering box fault | 0.03% |
| 111 | Brake valve fault | 0.02% |
| 112 | Indicator warning light fault | 0.02% |
| 113 | Towbar fault | 0.02% |
| 114 | Brake linkage mounting fault | 0.02% |
| 115 | Brake master cylinder or servo mounting fault | 0.02% |
| 116 | Propshaft fault | 0.02% |
| 117 | Brake master cylinder fault | 0.01% |
| 118 | Brake stationary pin worn | 0.01% |
| 119 | Wheel hub fault | 0.01% |
| 120 | Body strengthening plate corroded | <0.01% |
| 121 | Brake pressure or vacuum buildup insufficient | <0.01% |
| 122 | Brake slack adjuster fault | <0.01% |
| 123 | Catalytic converter efficiency low | <0.01% |
| 124 | Halfshaft fault | <0.01% |
| 125 | Radius arm worn or corroded | <0.01% |
| 126 | Seat belt anchorage fault | <0.01% |
| 127 | Seat belt load limiter fault | <0.01% |
| 128 | Semaphore indicator fault | <0.01% |
| 129 | Trailing arm worn or corroded | <0.01% |
| 130 | King pin or swivel pin worn | <0.01% |
| 131 | ABS fault | <0.01% |
| 132 | Access panel damaged or insecure | <0.01% |
| 133 | Additional braking device fault | <0.01% |
| 134 | Axle beam corroded or cracked | <0.01% |
| 135 | Axle corroded or damaged | <0.01% |
| 136 | Brake back plate corroded or damaged | <0.01% |
| 137 | Brake pedal linkage fault | <0.01% |
| 138 | Brake servo fault | <0.01% |
| 139 | Compression ignition emissions above threshold | <0.01% |
| 140 | Engine mounting worn or broken | <0.01% |
| 141 | Handbrake fails on gradient | <0.01% |
| 142 | Main beam warning light fault | <0.01% |
| 143 | Mirror or camera fault | <0.01% |
| 144 | Seat belt pre-tensioner fault | <0.01% |
| 145 | Steering intermediate drop arm worn | <0.01% |
| 146 | Stub axle worn | <0.01% |
| 147 | Suspension linkage attachment bracket or mounting corroded | <0.01% |
| 148 | Suspension unit fault | <0.01% |
Showing all 148 reasons — scroll inside the table for the full list.
Triumph Stag MOT Failures by Category
Total MOT failure occurrences for the Triumph Stag, 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 Triumph Stag problems?
Based on analysis of 72K Triumph Stag MOT tests from DVSA data, we have 40 identified common problems across 1 generation. The most frequently flagged issue is "Brake performance below minimum". Suspension is the most common problem category.
Which Triumph Stag generation has the most problems?
The Triumph Stag Stag (1970-1977) (1970–1977) has the highest number of identified common problems (50). 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 Triumph Stag?
Yes — use the "Tell Us About Your Problem" form on this page. Your report helps other Triumph Stag owners spot problems early. All submissions are reviewed before being added to the public database.
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