Diesel cars face stricter emissions test in the changes to the 2018 MOT

New changes to the MOT test

If your car is due an MOT, 2018 will see your vehicle face new defect categories and stricter emissions tests if it has a diesel engine. The new changes to the MOT test will come into effect on 20 May 2018.

New rules for diesel cars

The standard emissions tests will now be harder to pass for diesel cars, as lower limits are being introduced. If the exhaust on a vehicle with a diesel particulate filter is emitting smoke of any colour, it will be classed as a point for failure. This will make it tougher for anyone trying to cheat an emissions test, and will reduce the number of dangerous vehicles on the road.

The rules for diesel engines take into consideration the diesel particulate filter, how it works and whether it is doing its job properly. In 2014 rules were brought in which required the MOT tester to check that cars which were originally fitted with a DPF still had it in place. A number of car owners experienced difficulties with DPF failure so were removing them; the new rules were brought in as a measure to deter this. If the tester found the filter was removed it was classed as a failure.

The new rules in May will monitor whether during the test the filter emits smoke of any colour. If there are any signs of smoke it will be an automatic major fault, so the MOT test will be failed. The testers will also check the filter to see if there is any sign of damage or tampering. If the canister has been cut open and re-sealed, it may be refused a test. If the owner of the vehicle can prove that any damage was caused by legitimate filter cleaning, the test will be carried out.

New MOT fault categories

A new directive from the EU will be introduced which involves the use of categories to determine the seriousness of a fault. The categories will have a three-tier system comprised of minor, major and dangerous, with any fault classed as major or dangerous leading to an automatic failure.

The Driver and Vehicle Standards Agency (DVSA) are hoping this will lead to improved vehicle safety on the road. It is hoped that by classing serious defects as dangerous, the owner will be forced to fix the issue as a matter of urgency, and will not simply drive the vehicle away from the test station. Many service centres often offer to fix issues and retest on the same day, or as soon as possible, reducing the inconvenience of a motorist’s car being off the road. Together with the new directive, this should encourage drivers to take greater responsibility for vehicle safety.

Carwise Group offers a range of aftersales services at our centres in Harlow and Maidstone. If you would like to find out more about how the MOT 2018 changes will impact your vehicle, or book in some maintenance work, we will be more than happy to help.