All cars registered after 1992
require a catalytic converter to be fitted.
All cars registered after March 2001
must only replace catalytic converters with one that is E mark approved by a European Type Approval authority [Source: vca.gov.uk](this is not yet part of the MOT requirement but is a legal requirement). Catalytic Regulations
All diesel vehicles which were originally fitted with a diesel particulate filter (DPF) must have the DPF in place at the time of the MOT test. The vehicle will automatically fail the MOT test if the filter had been fitted as standard but is found to be no longer present.
The Vehicle inspectorate has also introduced in 2008
an amendment to the RfR (Reason for Rejection) regarding Regulation 54(2) of the Road Vehicles (Construction and Use) Regulation 1986 which states "Every exhaust system and silencer..................shall not be altered to increase the noise made by the escape of exhaust gases".
The MOT tester must now asses the level of exhaust noise at all engine speeds required for the emissions check and compare it to a similar vehicle fitted with a standard exhaust and the vehicle "should be failed if the noise emitted is clearly unreasonably above the level expected from a similar vehicle with a standard silencer in average condition". This means that if you have a great big fat noisy decatted exhaust then expect to get an MOT failure sheet!
(Your car will need to have a more standard exhaust fitted in order to pass the MOT. In most cases this is something that we can organise).