MOT cost .

Porsche

928 S

658 MOT tests analysed. lands in the middle of the pack — here's where 928 Ss pass, fail, and end up on the retest sheet.

That's 3.2 points above the UK fleet average across our 1,988 tracked models — a confident result.

Pass

78.9%

Pass-after-fix

3.6%

Fail

16.0%

Avg miles

107,854

Pass + Pass-after-fix + Fail = 100%

The picture

928 S: middle-of-the-pack on first-time pass

Across 658 MOT tests, the 928 S returns 78.9% first-time pass — roughly in line with the UK fleet average. The single most-logged Major fail is a split CV-joint boot. An obligatory rear fog lamp missing and windscreen washers not working round out the top three. Average tested mileage sits at 107,854, 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.

  1. 01

    A transmission shaft constant velocity joint boot severely deteriorated

    31 occurrences · 4.7% of tests

  2. 02

    An obligatory rear fog lamp missing, or a front or rear fog lamp inoperative or in the case of a multiple light source more than 1/2 not functioning

    22 occurrences · 3.3% of tests

  3. 03

    Windscreen washers not working or not providing sufficient fluid to clear the windscreen

    20 occurrences · 3.0% of tests

  4. 04

    A rear registration plate lamp or light source missing or inoperative in the case of multiple lamps or light sources

    19 occurrences · 2.9% of tests

  5. 05

    The aim of a headlamp is not within limits laid down in the requirements

    15 occurrences · 2.3% of tests

  6. 06

    Steering rack gaiter or ball joint dust cover damaged or deteriorated

    14 occurrences · 2.1% of tests

  7. 07

    The aim of a headlamp is not within limits laid down in the requirements

    12 occurrences · 1.8% of tests

  8. 08

    Steering rack gaiter or ball joint dust cover damaged or deteriorated

    11 occurrences · 1.7% of tests

  9. 09

    Windscreen washers not working or not providing sufficient fluid to clear the windscreen

    11 occurrences · 1.7% of tests

  10. 10

    Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view

    10 occurrences · 1.5% 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

£18–£115

If every one of this 928 S'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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Build your own retest budget.

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.

Item 01 · Amazon UK

H7 / W21W bulb pack

A spare-bulb kit lives in the boot. Test morning is not the time to find your stop-lamp's gone.

Search Amazon UK

Item 02 · Amazon UK

Headlight restoration kit

Yellowed lenses fail the light-output test. A restoration kit lifts the haze in an afternoon for £20.

Search Amazon UK

Buying or keeping a 928 S?

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 928 S 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.