MG B MOT pass rate & common failures

At a glance

Recorded pass rate

We are not publishing a ranking for the B. The examples tested do not cover a wide enough spread of ages and mileages to compare it fairly, and an unadjusted pass rate mostly sorts models by how recently they were bought rather than how well they were built. The failure and advisory patterns below come from the same 3,894 tests and are worth reading on their own terms.

DVSA recorded wording

Most common failure items

Share of failed MG B tests in which each item was recorded. One failed test often lists several items, so these do not sum to 100%.

1. 1.A lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning14.9%

   90 occurrencesLamp not working explained

2. 2.Emissions levels exceed default limits12.6%

   76 occurrencesEmissions above the permitted limit explained

3. 3.Windscreen washers not working or not providing sufficient fluid to clear the windscreen12.5%

   75 occurrencesWiper or washer not working properly explained

4. 4.Steering rack gaiter or ball joint dust cover missing or no longer prevents the ingress of dirt etc11.1%

   67 occurrencesSteering rack gaiter split, damaged or missing explained

5. 5.Significant brake effort recorded with no brake applied indicating a binding brake10.1%

   61 occurrencesBrake binding or imbalanced across an axle explained

6. 6.Brakes imbalance across an axle such that the braking effort from any wheel is less than 70% of the maximum effort recorded from the other wheel on the same axle10.0%

   60 occurrencesBrake binding or imbalanced across an axle explained

7. 7.Audible warning inoperative8.3%

   50 occurrencesHorn not working, or of the wrong type explained

8. 8.Stop lamps all missing or inoperative7.8%

   47 occurrencesStop lamp not working explained

9. 9.A headlamp or light source missing, inoperative or more than ½ not functioning in the case of LED7.3%

   44 occurrencesHeadlamp not working explained

10. 10.The aim of a headlamp is not within limits laid down in the requirements7.1%

    43 occurrencesHeadlamp aim incorrect explained

Warnings without a failure

Most common advisories

Share of all MG B tests carrying each advisory. The denominator differs from the failure list above because an advisory can be issued on a car that passed.

1. 1.Fluid leaking excessively and likely to harm the environment or to pose a safety risk to other road users12.4%

   481 tests

2. 2.A wheel bearing with excessive play6.0%

   235 testsWheel bearing has excessive play or is rough explained

3. 3.Fluid leaking excessively and likely to harm the environment or to pose a safety risk to other road users4.4%

   170 tests

4. 4.A tyre seriously damaged3.8%

   146 testsTyre damaged or deteriorated explained

5. 5.A suspension pin, bush or joint excessively worn3.6%

   140 testsSuspension arm bush worn explained

6. 6.Play in steering rack inner joint(s)2.6%

   102 tests

7. 7.Brake pipe damaged or excessively corroded2.5%

   98 testsBrake pipe corroded explained

8. 8.A shock absorber damaged to the extent that it does not function or showing signs of severe leakage2.3%

   88 testsShock absorber defective explained

What gets tested

The B fleet

Average mileage recorded at test

44,234

Across examples of every age, so this is a description of the fleet rather than an annual figure.

Fuel mix of tested cars

Petrol100.0%

Compare within the range

Other MG models

• MG ZS — 82.1% unadjusted
• MG HS — 88.3% unadjusted
• MG 3 — 75.1% unadjusted
• MG 5 — 84.3% unadjusted
• MG TF — 69.6% unadjusted
• MG Mgf — 66.9% unadjusted
• All MG models →

Common questions

How reliable is the MG B compared with other cars?

We do not publish a comparison for the MG B, because the cars of this model that have been tested do not cover a wide enough range of ages and mileages. Its raw pass rate is 82.3% across 3,894 tests, but comparing a raw rate between models mostly ranks them by how new they are rather than how good they are. The failure and advisory patterns further down the page are still drawn from real tests and are worth reading.

What is the most common MOT failure on a MG B?

The item recorded most often is "A lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning", which appears in 14.9% of failed MG B tests. Because one failed test can list several items, these shares do not add up to 100%.

What do testers most often warn about on a MG B?

The most common advisory is "Fluid leaking excessively and likely to harm the environment or to pose a safety risk to other road users", noted on 12.4% of all MG B tests. An advisory is not a failure: it flags something that will likely need attention before the next test.

What mileage does a MG B usually have at its MOT?

The average odometer reading recorded at test is 44,234 miles. This is the mileage across all tested examples of every age, not an annual figure, so treat it as a description of the fleet rather than a target for one car.

How this was worked out

Method and limits

Figures come from the DVSA anonymised MOT testing dataset, published under the Open Government Licence. Only class 4 initial tests are counted: retests are excluded so a car appears once, and abandoned tests are excluded entirely. No adjusted rate is shown because this model's tested examples do not cover enough of the national age and mileage range for standardisation to mean anything.

An MOT measures whether a car met a legal standard on the day. It is not a breakdown record, a service history or a running-cost estimate, and a pass rate is a property of a fleet rather than a prediction about one car.

Further reading

Make sense of the numbers

• How to judge reliability from evidence rather than reputation
• What counts as high or low mileage for a car’s age
• The most common MOT failures and how to avoid them
• What to check before buying a used MG