Why Some MOT Defects Remain Difficult to Spot

Some vehicle faults can be deceptive in nature, meaning they occur without warning. A car may drive normally despite a developing uneven tyre wear pattern, a deterioration in the condition of suspension bushes or even a developing fault in one of the vehicle’s lights. Some issues may only present themselves under the conditions that they are tested under, which is another reason an MOT is not a replacement for regular maintenance. The MOT only tests certain aspects of a vehicle to confirm it meets the requirements of the road. Learning more about where less obvious defects tend to creep up is useful for drivers, as it means they avoid potential MOT surprises.

Less Obvious Defects Before Testing

An MOT test looks over a specific set of items for a vehicle, not an overall mechanical specification. This causes some defects to appear later. A driver may not notice a developing issue with the same regularity they might notice a sudden fault with the engine or transmission. It is usually harder to identify developing mechanical faults, such as uneven tyre wear, as the changes may have been gradual. The same could be said for the changes in the condition of the suspension and brakes.

MOT Fails Without Warning

Not all MOT failures present themselves with a noticeable defect, odd noise, or change in condition. Tyres are a good example, as an uneven wear pattern forming on a tyre may not be readily apparent to the driver at any given point. The same could be said for a worsening set of suspension bushes or joints. The condition of the vehicle’s bodywork can also fail to present itself for similar reasons. A defect forming underneath or around a wheel or suspension component may only be noticed during a closer inspection of those components. For these reasons, the lack of immediately apparent issues is no reason to assume all is well with the vehicle in all respects.

Mechanical Wear Beneath Symptoms

Vehicle components do not typically degrade at a steady rate. Components usually hold together and perform normally until they start to wear faster or reach points where the changes have a noticeable effect on the overall performance of the vehicle. One of the most common examples of this involves tyres. A set of tyres can easily exhibit patchy wearing patterns or one-sided patchy wear without showing any signs of failure. However, most drivers would only associate a rapidly approaching MOT failure with the sudden loss of performance from their tyres, with the loss of performance being a direct result of the condition of the tyres. The same can be said for brakes, since the gradual loss of performance behind the wheel is rarely noticed until it becomes obvious during the MOT.

Looking Behind the Numbers of a Fault Inspection

As mentioned, some of the common vehicle defects are insidious in nature. Modern computerised diagnostic systems provide a helpful insight into some of the aforementioned issues, but they are not definitive. A diagnostic code provides the technician with an idea of what might be wrong with the vehicle based on a set of observed circumstances, not an explicit statement of what is wrong with it, because in many cases multiple components can fail together. This has little bearing on the ability to diagnose most mechanical issues. After all, most of the common vehicle defects that result in an MOT failure are mechanical in nature, including uneven tyre wear, faulty brakes, and many other similar issues. It is the examination of the actual components that allows the technician to identify and assess potential issues with the vehicle.

Routine Checks Before Testing

Making routine maintenance checks can enable drivers to locate less apparent defects before the MOT. For those local motorists visiting reliable centres like Allens of Tadley, an MOT is ideal in as much as it ensures they meet the current road requirements, but it only covers a specific set of the vehicle’s attributes. It makes sense for drivers to go over other aspects of their vehicle’s condition ahead of time. The driver can make a routine inspection before an MOT that covers the conditions of the following:

• All tyres, including their pressure and overall appearance
• Brakes and presence of unusual braking effects
• Suspension and its components
• All exterior lamps
• Windscreen, washers and wipers
• Lights on the dashboard

They are all useful touches ahead of an MOT, although there is no guarantee of an MOT pass. After all, the purpose of an MOT is to test whether a vehicle meets the minimum requirements on the road. Routine maintenance checks ensure a driver keeps their vehicle in good working order between MOTs.

Conclusion

Some of the most common vehicle defects are hard to notice, as they usually occur without warning. Many of them only present themselves upon inspection, including uneven tyre wear, the gradual degradation of several vehicle components, and much more. An MOT provides an independent assessment of a vehicle’s condition but only covers a specific set of criteria. Making routine maintenance checks enables the driver to have a more comprehensive knowledge of their vehicle’s condition and helps them prepare for a closer examination during an MOT.