MOT testers must either replace their diesel smoke meters, or update the software for the new tests. The main changes involve Euro V and VI emissions. As before, the visual check for missing, or tampered with DPFS continues and, if the canister has been cut open for legitimate reasons, the tester might request that evidence be provided of the work carried out. Similarly, any other emissions component – such as an EGR valve and SCR catalyst – that is missing, or defective, will result in a test fail.
The new limits apply as follows, except in cases where a smoke ‘K Value’ is provided on the VIN, as pictured within the box on this Opel’s plate (see above right). If a value is provided and it is higher than that of the MOT limit, the car will be tested according to the lower value.