At a Glance
The Triumph Stag has 40 identified problems that occur more often than the UK average, with Brake performance below minimum being the most reported. Electrical is the most common MOT failure category. Based on 67K MOT tests from DVSA data.
Problems are patterns in the DVSA data that occur significantly more often on this model than the UK average — confirmed at 99% statistical confidence. Read how we calculate MOT pass rates and problems →
Below: the full MOT-data picture for the Triumph Stag — MOT pass rate vs the UK average, common problems vs UK fleet patterns, the most likely MOT failures by frequency, fault occurrence by mileage band, and pass/fail trends. All numbers drawn from DVSA records.
Triumph Stag MOT Pass Rate
Across 67K MOT tests from DVSA data, the Triumph Stag (1970–1977) has a fail rate of 28.2%.
All-time UK average fail rate: 34.9%
Common Triumph Stag Problems
Owner-submitted reports plus patterns we've identified across 559 million UK MOT tests. Each MOT-derived item below — whether tagged as a Problem, Wear & Tear or Consumable — shows up noticeably more often on this generation than across the UK fleet, which is why it's here. Owner reports are pinned to the top by default; use the sort and filter pills below to view a specific tier or change the order.
Brake performance below minimum
3,958
occurrences
Windscreen washer not working
3,371
occurrences
Indicator fault
3,003
occurrences
Stop lamp not working
2,443
occurrences
Wiper blades deteriorated
1,957
occurrences
Tell Us About Your Problem
Help other Triumph Stag owners — report a problem and we'll add it to the database
Tell Us About Your Problem
Help other Triumph Stag owners — report a problem and we'll add it to the database
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Problems by mileage
Common problems, MOT failures and advisories on the Triumph Stag, grouped by the mileage they typically appear at.
493 distinct problems · 93,625 total occurrences in current filter
Filter by fuel and engine size to narrow down to your car.
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Advisory items are MOT tester observations. Frequency can be influenced by driving style and usage patterns.
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Frequently Asked Questions
What are the most common Triumph Stag problems?
Based on DVSA MOT data for the Triumph Stag Stag (1970–1977), we have identified 40 common problems. The most frequently reported is "Brake performance below minimum". Electrical is the most common MOT failure category.
How reliable is the Triumph Stag?
This generation has 67K MOT tests on record with a 28.2% fail rate. A fault is flagged as a "Common Problem" only when it occurs significantly more often on this model than the UK average, confirmed at 99% statistical confidence.
What commonly fails the MOT on a Triumph Stag?
There are 157 distinct MOT failure types recorded for the Stag (1970–1977), grouped by the mileage these failures typically occur. See the Common MOT Failures section on this page.
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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