Mechanics CornerNews

UK MOT Changes 2018


On the 20th May 2018, new MOT rules were introduced as part of the EU’s road worthiness directive. Due to the UK still being a full member of the union despite voting the leave, the rules have therefore stayed in full effect until future changes are made. Many vehicles owners won’t even be aware of these changes, especially if their car passed with no advisories after the 20th May 2018. Anyway, it’s always a good idea to know what to look out for when the MOT day nears closer.

New Rule #1 – New Defect Categories

The main change is the addition of new ‘defect categories’ instead of the previous fail and advisory statuses given to failing or completely failed parts. The new ‘dangerous’ category means you’re not actually allowed to drive the vehicle at all until it’s been repaired first, and this means a BIG problem for MOT test stations who purely perform MOT’s and don’t offer any repair or servicing work. The car would need to be trailered back to a garage that does do repair work, or trailered back home. The best advice from now on is to always go to a garage that performs servicing and repairs, but one that also performs MOT’s.

This is a perfectly acceptable new rule that was introduced for obvious safety reasons, just google MOT horror stories for an explanation!

Item result What it means about the item How it affects your MOT result
Dangerous A direct and immediate risk to road safety or has a serious impact on the environment. Do not drive the vehicle until it’s been repaired. Fail
Major It may affect the vehicle’s safety, put other road users at risk or have an impact on the environment. Repair it immediately. Fail
Minor No significant effect on the safety of the vehicle or impact on the environment. Repair as soon as possible. Pass
Advisory It could become more serious in the future. Monitor and repair it if necessary. Pass
Pass It meets the minimum legal standard. Make sure it continues to meet the standard. Pass


New Rule #3 – Stricter Rules for Diesel Car Emissions

There are now stricter limits for the emissions from diesel cars that are fitted with a diesel particulate filter (DPF). A DPF captures and stores the exhaust soot to reduce emissions from diesel cars. Check your car’s handbook to know if your car has a DPF fitted.

Your vehicle will get a major fault if the MOT tester:

  • can see smoke of any colour coming from the exhaust
  • finds evidence that the DPF has been tampered with

This means that after market exhaust systems that remove the DPF can no longer be legal in the UK.


New Rule #4 – MOT Exemption on Vehicles over 40 Years Old*

For classic car enthusiasts, this confusing new rule was added which exempts vehicles over 40 years old from needing an MOT, BUT only if they haven’t been ”substantially changed’ in the last 30 years.

But what actually defines as being substantially changed?

“A vehicle alteration is a ‘substantial change’ if the technical characteristics of the main components have changed in the previous 30 years, unless these fall into the ‘acceptable alterations’ category.”

Substantial Change Criteria (Excluding Motorcycles)

Axles and Running Gear

  • Alteration of the type or method of suspension and steering is counted as a ‘substantial change’ and will require an MOT test.


  • Alternative cubic capacities of the same basic engine (rebores, sleeving) and alternative original equipment engines are not considered to be a substantial change, therefore won’t require an MOT test.
  • However, if the number of cylinders in the engine is different from the original, it’s likely to be counted as a substantial change, especially if the engine is not an alternative original equipment engine. For a far fetched example, a V8 engine from a Mustang that’s been fitted into Mk1 Escort would need an MOT test.


Other ‘substantial change’ criteria (all vehicles)

A vehicle is considered to have been ‘substantially changed’ if it:

  • has been given a ‘Q’ registration number
  • is a kit car assembled from components from different makes and model of vehicle
  • is a reconstructed classic vehicle as defined by DVLA guidance
  • is a kit conversion, where a kit of new parts is added to an existing vehicle, or old parts are added to a kit of a manufactured body, chassis or monocoque bodyshell, which changes the general appearance of the vehicle
  • However, if a vehicle meeting one or more of these criteria is taxed as a ‘historic vehicle’, and it has not been modified during the previous 30 years, it is exempt from needing an MOT.

‘Acceptable Alterations’

It does not count as a ‘substantial change’ and will not require an MOT if:

  • changes are made to preserve a vehicle because the original type parts are no longer reasonably available
  • they are changes of a type which can be demonstrated to have been made when vehicles of the type were in production or within 10 years of the end of production
  • axles and running gear have been changed to improve efficiency, safety or environmental performance
  • changes were made to vehicles that were previously used as commercial vehicles, and you can prove the changes were made when the vehicle was used commercially

All in all it’s still a very confusing new rule and the likelihood is that you’ll probably want to contact the DVSA for direct confirmation, because whoever wrote the article about it has made some points quite unclear and even more of a headache.


New Checks Included in the MOT

Some new items are now tested during the MOT.

They include checking:

  • if the tyres are obviously under inflated
  • if the brake fluid has been contaminated
  • for fluid leaks posing an environmental risk
  • brake pad warning lights and if brake pads or discs are missing
  • reversing lights on vehicles first used from 1 September 2009
  • headlight washers on vehicles first used from 1 September 2009 (if they have them)
  • daytime running lights on vehicles first used from 1 March 2018 (most of these vehicles will have their first MOT in 2021 when they’re 3 years old)

There are other smaller changes to how some items are checked. Your MOT centre will be able to tell you about these.



  • The maximum fees MOT centres can charge won’t change.
  • In January 2018, the government decided to keep the age a vehicle needs its first MOT at 3 years, rather than extend it to 4 years.
  • You can get a free MOT reminder by text message or email a month before your MOT is due.


Leave a Comment