MOT Advisory vs Failure: What's the Difference and Should You Worry?

If you have ever collected your car from an MOT test and been handed a certificate covered in notes, you are not alone. Understanding the difference between an MOT advisory and a failure is essential for every UK driver — and for anyone buying a used car. Get the distinction wrong and you could either panic-repair items that do not yet need attention, or drive away in a vehicle that legally should not be on the road.

Since May 2018, the UK MOT test has used a three-tier defect classification that replaced the old binary pass/fail/advisory system. Here is a complete explanation of each tier and what it means for you.

The Three-Tier Defect System

Advisory

An advisory is a note that a component is showing early signs of wear or deterioration but is not yet at the point of failure. The vehicle passes its MOT with advisory items recorded. You can continue driving legally. However, advisories exist to alert you that something needs monitoring — they are a prediction of future failure, not a current one.

Common advisory items include: tyre tread approaching minimum depth, slight brake disc corrosion, minor oil seepage from an engine gasket, and a slightly stiff suspension component. None of these prevent the car from passing, but all should be addressed before the next test.

Major (Failure)

A major defect results in an MOT failure. The vehicle may affect road safety or the environment, and it must be repaired before it can be re-tested. However — and this is a detail many drivers miss — a car that fails on major defects can still be driven legally, provided its previous MOT certificate has not expired. If you fail your MOT during the final month of your certificate's validity, your old certificate remains in force and you can drive home and arrange repairs.

If your previous certificate has already expired and you fail on major defects, you cannot legally drive the vehicle except to a pre-arranged repair appointment or a re-test booking.

Dangerous (Failure)

A dangerous defect is the most serious classification. It represents an immediate road safety risk and the vehicle must not be driven until it is repaired — regardless of whether your previous certificate is still valid. The tester will note the dangerous defect on the VT30 failure certificate, and driving the vehicle knowingly with a dangerous defect is a criminal offence carrying an unlimited fine and three penalty points. Your insurance may also be invalidated.

Should You Be Worried About an Advisory?

The degree of concern an advisory warrants depends on the specific item and how close to the failure threshold the component is. Here are some rules of thumb:

• Tyre tread advisory: If the note says "tyre approaching legal limit", check the depth yourself with a tread depth gauge (available for under £5). At 2 mm or below, replacement should be imminent. At 2.5–3 mm, you have some time but should budget for replacement soon.
• Brake disc corrosion advisory: Light surface corrosion on discs is extremely common and usually resolves with normal driving. If the advisory notes "heavy pitting" or "significant scoring", have a mechanic inspect before the next test.
• Oil leak advisory: A minor seepage is different from an active drip. Monitor the oil level more frequently and investigate if consumption increases.
• Suspension wear advisory: These tend to deteriorate. A bush noted as "worn, monitor" in year one may be a failure item by year two. Get a suspension check if the car develops a knock.

MOT Advisory vs Failure When Buying a Used Car

The MOT advisory vs failure distinction takes on extra significance when you are assessing a used car purchase. A car with a valid MOT but a long list of advisory items may actually carry higher repair liability than a car that recently failed and had everything rectified.

When reviewing a vehicle's history, look for advisory items that persist across multiple test years without being resolved. An advisory recorded for the same component across three consecutive tests suggests either deliberate neglect or that repairs were never made. You can review any car's full advisory and failure history using our MOT history check.

How Long Do You Have to Fix a Failure?

There is no fixed deadline to repair a major or dangerous defect from the MOT test itself. However, the practical constraints are:

• You cannot drive a vehicle with an expired MOT certificate (except to a pre-booked test or repair)
• You cannot obtain a new MOT certificate until all major and dangerous defects are repaired
• A vehicle with dangerous defects must not be driven for any purpose until repaired

If a failure item is repaired at the original test station within ten working days, the re-test is usually free (or at a reduced fee) for the specific items that failed. A fresh test at a different station, or after the ten-day window, is charged as a full re-test.

Checking Your Car's Advisory History Online

Every advisory and failure item from every MOT test is stored permanently in the DVSA database and is publicly accessible. Before your next test, review your car's existing advisories via our free MOT check to understand what areas testers have flagged in the past and prioritise your pre-test preparation accordingly. Pairing this with our common MOT failures guide will give you a clear action list before your car goes in for its test.