The picture
911: a strong MOT record by UK norms
Across 52,087 MOT tests, the 911 returns 87.8% first-time pass — comfortably ahead of the UK fleet average. The single most-logged Major fail is windscreen damage. A corroded brake pipe and a number-plate lamp out round out the top three. Average tested mileage sits at 60,423, which is the lens to read those failure rankings through. If you own one and the next test is close, the ranked list below is a sensible pre-test checklist.
Top ten reasons for rejection.
- 01
Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view
919 occurrences · 1.8% of tests
- 02
Brake pipe damaged or excessively corroded
595 occurrences · 1.1% of tests
- 03
A rear registration plate lamp or light source missing or inoperative in the case of multiple lamps or light sources
592 occurrences · 1.1% of tests
- 04
Lambda coefficient outside the default limits or the range specified by the manufacturer
548 occurrences · 1.1% of tests
- 05
A transmission shaft constant velocity joint boot missing or no longer prevents the ingress of dirt etc
527 occurrences · 1.0% of tests
- 06
Tyre tread depth not in accordance with the requirements
491 occurrences · 0.9% of tests
- 07
A transmission shaft constant velocity joint boot severely deteriorated
438 occurrences · 0.8% of tests
- 08
A tyre cords visible or damaged
434 occurrences · 0.8% of tests
- 09
A lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning
422 occurrences · 0.8% of tests
- 10
The aim of a headlamp is not within limits laid down in the requirements
388 occurrences · 0.7% of tests
Counts cover Major and Dangerous defects logged at test. Advisory items excluded so this shows why a car was rejected, not just what the tester flagged in passing.
Worst-case fix budget · top 2 failures
£48–£125
If every one of this 911's most-logged Major fails hit at the same MOT, that's the real-world UK garage range. Reality is usually one or two items, not all of them. Open the estimator →
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Tools that pre-empt a retest.
Picked against this car's top failure patterns. Affiliate links to Amazon UK — we earn a small cut at no cost to you. Disclosed up-front, doesn't shape the data.
Buying or keeping a 911?
Use the failure ranking as a pre-test checklist or a haggling lever. Treat the headline pass rate as a fleet-wide trend, not a guarantee on any individual car.
If you own a 911 and your last MOT looked nothing like the ranked failures above, that's normal — individual cars vary widely. The ranking shows the patterns testers flag most often across the country.