New MOT test rules will target DPF cheats

Car exhaust

New MOT rules will come into force from 20 May 2018. These will include stricter checks on emissions for newer diesel vehicles. There will also be a specific check to make sure that diesel cars which were sold with a diesel particulate filter (DPF) have not had these removed or modified (e.g. gutted or bypassed).

DPF’s are designed to burn away the soot that’s produced when you start a cold diesel engine. As a rough guideline, they’ve been fitted to new diesel cars since 2009. But they’re a headache for drivers who do mainly do short journeys from cold, as these filters don’t get hot enough to burn up the ash and instead become clogged up. The reality is that they’re were never designed for this kind of use.

However, having your DPF cleaned or replaced is an expensive job. And because the car will run fine without it, some drivers have taken to removing or bypassing their DPFs. Although this was always illegal, it wasn’t always detected by standard MOT checks, so you could often get away with it. That’s about to change.

The new MOT rules include a tougher emissions test for newer diesel vehicles and a specific check to see if the DPF has been tampered with. So owners of cars without a working DPF should expect their car to fail its MOT from 20 May 2018 onwards.

What else is changing in the new MOT?

A number of new checks will be introduced, including

The other big change that’s coming in the new-look MOT is that the test results categories will change.

Previously your car would pass or fail. You might receive advisories on potential problems, but these wouldn’t stop you from passing.

The new system is a bit different and is intended to make drivers more aware of the potential safety or environmental risk caused by faults with their vehicles. There will be five categories of MOT test result. I’ve indicated whether this will result in a pass or a fail at the end of each line:

  • Dangerous: Using the car would carry a serious road safety or environmental risk. Do not drive the car until it’s fixed. [FAIL]
  • Major: The car has a fault that could affect safety, put other road users at risk or have an impact on the environment. Get it fixed immediately. [FAIL]
  • Minor: There is a fault but it isn’t a safety risk and doesn’t have any impact on the environment. Get it fixed when possible. [PASS]
  • Advisory: A minor issue or a wear and tear item that could need attention in the future. [PASS]
  • Pass: The car passes all the tests without problems. [PASS]

I have to admit that I don’t really understand the benefit of having so many categories. But this is how the MOT testing system will work from next week (20 May 2018 onwards).

Reminder: Driving without a valid MOT is illegal. This means that driving without an MOT will also invalidate your insurance. So if you’re caught, you’ll face penalties for uninsured driving. And if you’re in an collision, you could be liable for all the costs arising from the incident.

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