How to Reduce Your Emissions for an MOT

The amount of emissions your car produces isn’t just about saving the planet, it can mean the difference between a pass and fail on your MOT too with high emissions being classed as a major fault.

car exhaustIn the six months after changes were made to the UK MOT test in May 2018, 750,000 cars failed on emissions testing compared to 350,000 from the same period the previous year –an increase of 114%. And diesel cars faired the worse, with a 63% increase in MOT failures for diesel engines.

So if your MOT’s due soon it’s good to be aware of the emissions testing and how you can give your car the best chance of passing.

Why Are More Cars Failing the MOT Test?

In May 2018, the UK’s standard MOT underwent a drastic overhaul as part of the EU Roadworthiness Package, with tighter regulations seeing cars submitted to a new set of failure and defect categories. Some of the biggest MOT test changes were made to the emissions portion of the test, with stricter rules in place to penalise cars which don’t meet the emissions criteria.

Diesel car drivers have felt the impact of the new MOT emissions rules more than most, with legislation in place to reduce harmful emissions from this type of engine. Greater scrutiny is now placed on the health of diesel engines, including visible tailpipe emissions (smoke), the engine management warning light, and the diesel particulate filter (DPF).

Petrol cars didn’t escape MOT test changes either, though. Now, cars that emit oily or blue smoke for over five seconds can receive a ‘major’ fault on the MOT test, which is classified as a fail.

A mechanic checking the exhaust for fumes

What Are the Rules on MOT Test Emissions?

Here are the rules on MOT test emissions you need to know:

  • Your car must not have visible smoke coming from the exhaust
  • Your car must not exceed the emissions restrictions for diesel or petrol engines
  • Your car’s DPF must not have been tampered with or removed
  • Your car must not display an engine management light, which signals a problem with the emissions system and DPF

In most cases, issues affecting a car’s emissions are treated as ‘major’ or ‘dangerous’ under new MOT test guidelines – meaning your car will fail the test. The government has taken a tough stance on emissions to align with its carbon-reduction targets.

Here’s a look at the new MOT defect categories, introduced in May 2018:

Defect CategoryDefect DescriptionTest Result
MinorNo significant effect on the safety of the vehicle or impact on the environment.Pass – Fault should be repaired as soon as possible.
MajorMay affect the vehicle’s safety, put other road users at risk, or have an impact on the environment. Most emissions issues fall into this category.Fail – Repair immediately. The car can be driven home, but should only be used again for driving to the rescheduled test.
DangerousDirect and immediate risk to road safety or poses a serious impact on the environment.Fail – The car cannot be driven until it has been repaired.

How to Reduce Your Car’s Emissions for an MOT

Good car maintenance is the starting point for emissions and efficiency.

  • Regular oil checks
  • Regular services
  • Dealing quickly with issues such as exhaust repairs

will all help to keep your emissions down. But cleaning inside your fuel system and keeping it working as efficiently as possible is crucial, especially when you’re preparing your car for its MOT. Our new Pre-MOT product gives a deep clean to lower your emissions which may help you pass first time.

Redex Pre-mot dieselA bottle of redex pre-mot petrol

Using our super-strength Pre-MOT in the run up to your test will:

  • Reduce exhaust emissions
  • Restore engine performance
  • Improve the life of the engine
  • Can help your car pass its MOT

Like all Redex fuel additives, Pre-MOT can be added to your car through the fuel filler cap. The bottle’s unique shape allows you to add the right amount, and from there, the product will circulate through the fuel system and engine as you drive – removing particles and cleaning components to ensure your car’s emissions are as they should be.

As well as our new Redex Pre-MOT formula, you can also use Redex Advanced as a long-term solution for keeping your car’s emissions in check. Available for both petrol and diesel cars, our advanced formula provides the following benefits:

Redex Advanced PetrolRedex Advanced Diesel
·      Friction Modifier improves engine performance by lubricating the components in the combustion chamber

·      Advanced formula

·      Complete system clean

·      Helps your car pass its MOT

·      Quickly cleans and clears soot blockages in the DPF filter

·      Switches off your car’s engine management warning light

·      Advanced formula

·      Complete system clean

·      Helps your car pass its MOT

Used every 3,000 miles, Redex Advanced can improve the life of your car’s engine and help to lower emissions as well.

Check out our blog for more motoring news and advice, or to learn more about our innovative fuel system cleaners and additives, visit the Redex homepage today.