COMMISSION OF THE EUROPEAN COMMUNITIES 
C0M(91) 244 final 
Brussels, 4 July 1991 
Proposal for a 
COUNCIL DIRECTIVE 
AMENDING DIRECTIVE 77/143 EEC ON THE 
APPROXIMATION OF THE LAWS OF THE 
MEMBER STATES RELATING TO ROADWORTHINESS TESTS 
FOR MOTOR VEHICLES AND THEIR TRAILERS 
(EXHAUST EMISSIONS) 
(presented by the Commission) 
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Explanatory Memorandum 
General Comments 
Actual Situation 
Directive 77/143/EEC*1>, as amended by Directive 88/449/EEC<2>, 
concerns the technical inspection of heavy goods vehicles, buses, 
taxis, ambulances and light goods vehicles. 
These Directives set the periodicity of tests and provide a list of 
the items to be tested. 
Given that Directive 77/143/EEC does not set standard criteria for any 
of the items that should be tested, it is thus necessary to set common 
minimum test standards in order to guarantee an equal level of safety 
and through this proposal, environmental performance throughout the 
Community. 
Directive 91/225/EEC<3> amending Directive 77/143/EEC, which was 
recently adopted by the Council, is aimed at the establishment of a 
procedure for the announcement of separate Directives for testing the 
standard of the items listed in Annex II of Directive 77/143/EEC. It 
also establishes a Technical Committee which gives the Commission the 
mandate to adopt measures in order to adjust the technical 
requirements to progress. 
In line with the above, this new proposal amends Annex II to Directive 
77/143/EEC as amended by 88/449/EEC so as to better define the limit 
values for the acceptable levels of gaseous emissions for spark 
ignition (petrol) and smoke opacity for compression ignition (diesel) 
engined motor vehicles. 
(1) OJ No. L47, 18.02.1977, p. 47 
(2) OJ No. L222, 12.08.1988, p. 10 
(3) OJ No. L103, 23.04.1991, p. 3 
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Scope of the proposal 
The scope of Directive 77/143/EEC as amended by 88/449/EEC includes 
heavy and light commercial vehicles (as well as taxis and ambulances) 
but does not include passenger cars. Passenger cars are the subject of 
an amending proposal C0M(86)214<4>. Adoption of C0M(86)214 will 
ensure that all motor vehicles, both passenger and commercial, are 
subject to the necessary emission checks. 
This proposal on testing the level of vehicle gaseous emissions or 
smoke opacity dovetails into the current and proposed roadworthiness 
schemes and so shares the same periodicity of testing. By the time 
this proposal is adopted, or soon after, the legislation affecting the 
manufacture of petrol engined passenger cars will be such as to force 
the use of closed loop 3way catalytic converter systems which are 
lambda probe controller for most, if not all, new vehicles. The type 
approval durability requirements for these vehicle emission control 
systems would support a three year in use start point before they need 
to be roadworthiness tested. 
Heavy commercial vehicles (and also taxis and ambulances) will need to 
be tested every year from the time of their first use, the diesel 
engined vehicles requiring to demonstrate their level of engine 
maintenance through a smoke opacity check. Light commercial vehicles 
(less than 3.5 tonnes) will require a test periodicity of at least 
commencing four years from first use and thereafter every two years. 
It is considered that the durability of diesel engined vehicles 
justifies this periodicity. 
Vehicles first used before 1st January 1970 will not be required to 
undergo an exhaust emission or smoke opacity check. However, Member 
States will be free to test these vehicles to their own national 
standards if they so wish. 
(4) OJ No. C 133, 31.05.t986, P„ 3 
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Limit values 
After much discussion with Member States National experts on 
roadworthiness testing, on vehicle construction standards and with 
representatives from the automobile and vehicle inspection industries 
it has been decided to set maximum vehicle gaseous emission and smoke 
opacity limit values which will ensure that the "gross polluters" will 
fail the test. The limits for Carbon Monoxide emissions for 
conventional petrol engined vehicles, at 4.5 vol % and then 3.5 vol %, 
reflect studies (in the UK) that have shown that some 50 % of CO emis­
sions comes from the worst 17 % or so of the petrol engined vehicles 
on the roads at the moment. Whereas those studies have also shown 
that around 25 % of current in service conventionally engined 
passenger cars have CO emission values worse than 4.5 vol %, bearing 
in mind that testing commences after the vehicles are 3 years oids it 
is anticipated that an initial failure rate of up to 50 % could be 
expected. Clearly it is in the publics interest to ensure that their 
vehicles are correctly adjusted and maintained. 
[As an a I ten ?ve to the 4.5/3.5 vol % CO limits, the maximum content 
of CO in the exhaust gas at idling shall be that stated by the vehicle 
manufacturer and recorded at type approval testing. This alternative 
is always equal to or lower than the 4.5/3.5 vol % limit.] 
For petrol engined vehicles with advanced emission control systems, 
ie. with closed loop 3-way catalytic converter which are lambda (air/ 
fuel ratio) probe controlled, the limit CO valve of 0.3 vol % reflects 
the need to maintain the quantum leap in vehicle emission reduction 
brought about by the introduction of this new technology. 
For vehicles with diesel engines this proposal adopts the philosophy 
of judging the maintenance condition of the vehicle, and hence its 
ability to be a low polluter, by measuring the opacity of its exhaust 
smoke. 
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The Mmit values of >-.e coefficient of absorption of the generated 
jmoke of 2.5 m~1 for natural y aspirated diesel engines and 3.0 m~1 
for turbo charged diesel engines take account of the imprecision of 
the free acceleration test as a predictor of in service conditions, in 
particular for turbo charged heavy commercial vehicles, but are 
sufficiently tight to again identify the gross polluters, vehicles 
that are responsible for most of the pollution emitted by vehicles in 
service. 
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PROPOSAL FOR A 
COUNCIL DIRECTIVE 
AMENDING DIRECTIVE 77/143/EEC 
ON THE APPROXIMATION OF THE LAWS OF THE 
MEMBER STATES RELATING TO ROADWORTHINESS TESTS FOR 
MOTOR VEHICLES AND THEIR TRAILERS 
The Council of the European Communities, 
Having regard to the Treaty establishing the European Economic 
Community and in particular Article 75 thereof, 
Having regard to the proposal from the Commission^1), 
Having regard to the opinion of the European Par I lament*2), 
Having regard to the opinion of the Economic and Social Committee*3^, 
Whereas, Council Directive 77/143/EEC(4> as amended by Directive 
88/449/EEC<5) provides for the regular roadworthiness testing of 
certain road vehicles only (buses, heavy and light goods vehicles, 
heavy trailers and semi trailers, taxis and ambulances) but not yet 
for passenger cars; 
Whereas, through Council Directive 91/225/EEC<6>, it is the intention 
to establish procedures for the announcement of separate Directives 
for testing the standard of the items listed in Annex II of the above 
Directives; 
Whereas, through the above directive it is also the intention to 
establish a Technical Committee which gives the Commission the mandate 
to adopt measures in order to adjust the technical requirements to 
progress: 
(1) OJ N" C ... 
(2) OJ N* C ... 
(3) OJ N* C ... 
(4) OJ N- L47, 18.2.1977, p. 47 
(5) OJ N' L222, 12.8.1988, p. 10 
(6) OJ N' L 103, 23.4.1991, p. 3 
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Whereas, by this Directive it is the intention to maintain the exhaust 
emission of vehicles at a low level during their useful life by means 
of a periodical exhaust emission test and ensure that vehicles which 
are gross polluters are removed from service until they are correctiy 
maintained ; 
Whereas, most Member States have adopted procedures for testing heavy 
commercial vehicles with regard to the opacity of their exhaust smoke-, 
Whereas, several Member States have national rules for testing the 
gaseous emissions from lighter vehicles including passenger cars; 
Whereas, assessment of the type approval testing for gaseous emissions 
and diesel smoke for all vehicle types shows that the reproduction of 
those testing procedures within the roadworthiness test is not 
realist ic; 
Whereas, standards that are dictated for in service testing should 
focus on the maintenance condition of the vehicle, and thereby its 
ability to meet type approval performance criteria, during a 
relatively simple, quick and inexpensive test; 
Whereas, wrong tuning of the engine and insufficient maintenance are 
detrimental to the engine and to the environment through increases in 
pollution and fuel consumption; 
Whereas, as far as diesel engines (compression ignition) are 
concerned, measurement of the opacity of the exhaust emissions is 
considered a sufficient indicator of the condition of the vehicles' 
emission control system; 
Whereas, for conventional petrol engines (spark ignition) the 
measurement of the vehicles' tailpipe emissions of carbon monoxide 
taken at engine idle speed, is considered to give a sufficient 
indication of the vehicles maintenance condition; 
Whereas, it is expected that the failure rate of the above vehicles 
retating to exhaust emissions could be high if the vehicle has not 
been subjected to routine marntenance; 
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Whereas, for petrol engined vehicles where- tNo type approval requi­
rements necessitate that they be equipped with advanced emission 
control systems such as closed loop, 3way catalytic converters which 
are lambda probe controlled, the standard for in service emission 
testing will be more severe than for conventional vehicles-, 
Whereas, it is the intention to adapt this Directive to take account 
of future developments on the provision of vehicle construction 
measures which facilitate in service inspection and advances in 
testing methodology designed to better reflect conditions in service 
Has adopted this Directive. 
Article 1 
1. Sub Paragraph 8.2 of Annex II to Directive 77/143 EEC as amended 
by Directive 88/449 EEC which concerns exhaust emissions is 
replaced by: 
« 9 
8.2 Exhaust Emissions 
8.2.1 Motor vehicles equipped with spark ignition (petro!) engines 
a) where the exhaust emissions are not governed by an advanced 
emission control system such as a closed loop three way 
catalytic converter which is lambda probe controlled. 
1. Visual inspection of the exhaust system in order to check 
that there are no leakages. 
2. Visual inspection of the emission control system if 
applicable in order to check that the necessary equipment is 
present. 
After a reasonable period of engine conditioning commensurate 
with the vehicle manufacturers recommendations the carbon 
monoxide (CO) content of the exhaust gases will be measured 
at engine idle speed (no load). 
The maximum allowable content of CO in the exhaust gases 
shall be that which is stated by the vehicle manufacturer and 
recorded at the time of initial type approval with a 
tolerance of 0.5 vol %. Where this data is not available or 
where Member States testing authorities decide not to use 
this data as a reference value then the exhaust gas content 
of CO must not be greater than the following : 
For vehicles manufactured prior to October 1986 or the date 
on which Member States required the vehicles at first 
registration to comply with the type approval Directive 
70/220/EEC<7> as amended : CO - 4.5 vol % 
(7) OJ Nr L 76 of 9.3.1970, p. 
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For vehicles manufactured after 1 October 1986 : 
CO - 3.5 vol % 
Vehicles manufactured prior to 1 January 1970 are exempted 
from these requirements. 
b) where the exhaust emissions are governed by an advanced 
emission control system such as a closed loop three way 
catalytic converter which is lambda probe controlled or where 
the vehicles' exhaust emissions are governed by some other 
method in order to comply with the type approval provisions 
of Directive 70/220/EEC as amended [by the consolidated 
emissions Directive*8*]. 
1. Visual inspection of the exhaust system in order to check 
that there are no leakages and that all parts are complete. 
2. Visual inspection of the emission control system in order 
to verify that the necessary equipment is present. 
3. Determination of the efficiency of the vehicles emission 
control system by measuring the lambda value and the CO 
content of the exhaust gases according to point 4 below or 
according to the manufacturers optional procedures as 
recorded at the time of initial type approval. The vehicle 
shall undergo a period of engine conditioning commensurate 
with the vehicle manufacturers recommendations for each of 
the tests. 
4. Tail pipe emissions - limit values 
- Measurement at engine idle speed ; 
The maximum allowable content in the exhaust gases of CO 
shall be that which is stated by the vehicle manufacturer 
and recorded at the time of initial type approval. 
Where this data is not available then the CO limit of 0.5 
vol X should not be exceeded. 
(8) Council N' 4102/91 adopted by the Council on 4 March 1991. 
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Measurement at increased idling speed without engine load 
engine speed to be at least 2000 r.p.m. 
CO content : no greater than 0.3 vol % 
Lambda : I ± 0.03 or in accordance with the 
manufacturers specifications. 
8•2•2 Motor vehicles equipped with compression ignition (diesel) 
engines 
Measurement of exhaust gas opacity upon revving the engine 
with transmission in neutral (no load), i.e. the engine is 
accelerated from idling speed up to cut off speed. The level 
of opacity shall be no more than that which is stated by the 
vehicle manufacturer and recorded on the vehicle at the time 
of initial type approval with a tolerance of 
0.5 m ~1. Where this data is not available or where 
Member States testing authorities decide not to use this 
value as a reference than the following limit values should 
not be exceeded : 
Maximum coefficient of absorption for 
Naturally aspirated diesel engines - 2.5 m~1» 
Turbo charged diesel engines • 3.0 m" 
Vehicles manufactured prior to 1 January 1970 are exempted 
from these requirements. 
8.2.3. Test equipment 
The testing of both petrol engined and diesel engined 
vehicles will require the use of equipment capable of 
accurately testing vehicles against the prescribed or stated 
limit values. 
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Article 2 
1. Member States shall take the measures necessary to comply with 
this Directive before 1 January 1993. They shall forthwith 
inform the Commission thereof. 
2. When the Member States adopt the provisions referred to in 
paragraph 1, these shall contain a reference to this Directive or 
shall be accompanied by such a reference at the time of their 
official publication. The form of this reference sha11 be 
decided by the Member States. 
3. Member States shall communicate to the Commission the provisions 
of national law which they adopt In the field governed by this 
Directive. 
Article 3 
This Directive is addressed to the Member States 
Done at Brussels, For the Council 
The President 
Compet i t i veness and Cmplovment Impact Statement 
!. What is the main reason for introducing this measure? 
Whereas the build standard of vehicles, with regard to the emissions 
of gaseous pollutants, have improved over the years, the ability to 
maintain a reasonably low level of emissions from in service vehicles 
is tested only in a few Member States. It Is recognised as being of 
vital importance that vehicles continue to produce levels of 
emissions in service which can equate to their original type approved 
standard. Tests have shown that vehicles with conventional petrol 
engines can produce four times or more carbon monoxide than they do 
when new (although the level of nitrous oxides tends to fall slightly 
in service). A simple Justment is invariably all that is required 
to bring these vehicles back into tune. Modern petrol engined 
vehicles with catalytic converters (with lambda probe controlled 
air/fuel ratio) produce in the order of 1/10 the pollutants of 
conventional vehicles. It is important that this impressive standard 
is maintained in service as failure of the catalyst through lead 
poisoning, burn out etc can render the vehicle worse than those with 
relatively modern conventional engines. For diesel engines, dense 
clouds of smoke are the obvious manifestation of poor engine 
maintenance. This poor maintenance will invariably cause high levels 
of gaseous emissions (as well as soot and other particulates). Again 
this proposal aims at identifying the gross polluters. 
I I. Features of the business in question 
All users of vehicles, the subject of Directive 77/143/EEC as 
amended, also garages, technical services and agencies charged with 
vehicle roadworthiness testing will be affected. As things stand at 
the moment, only commercial vehicles, including taxis and ambulances, 
are covered by roadworthiness Directives. 
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The amendment to include passenger cars within a Community 
roadworthiness scheme remains on the table of the Council. Until this 
amendment is adopted this proposal on exhaust emissions will not 
affect owners of passenger cars nor those small businesses responsible 
for their operation or maintenance. 
111.What obligations does this measure impose directly 
on business? 
Users of vehicles, be they the general public or commercial operators 
will need to pay particular attention to the standard of maintenance 
of their vehicles' emission control/engine management systems. This 
is no more than should reasonably be done anyway for both 
environmental and fuel saving reasons. The cost of the roadworthiness 
test may rise (by approximately 20 %) for those Member States that do 
not currently test for vehicle emissions. Also, the testing 
agencies/garages will need to invest in equipment which, for testing 
vehicles with catalysts etc. could cost a further 7000 ECU. However, 
as yet passenger cars will be unaffected by this proposal until they 
are included within the roadworthiness scheme. 
IV. What indirect obligations are national, regional or local 
authorities likely to impose on business? 
Implementation of the obligations as described in III. 
V. Are there any special provisions In respect to SME's? 
Where roadworthiness testing is delegated to private garages, these 
garages will incur an extra cost for test equipment. However, that 
cost can be offset by increased fees. 
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VI. What Is the likely effect on: 
a) The competitiveness of business 
The extra complexity of testing for exhaust emissions will increase 
the cost of the roadworthiness test for commercial vehicle operators 
by approximately 20 %. This will apply to passenger car operators as 
and when these vehicles are included in the roadworthiness scheme. 
This proposal will equalise the conditions of competition by 
standardising on the type of test to be applied. 
Certain EFTA countries (Sweden, Norway, Switzerland and Austria) carry 
out or are intending to carry out emission testing on the lines of the 
proposal. 
b) Employment 
Possibly a marginal increase commensurate with the increased time to 
test the vehicles. 
VII.Have the relevant representation organisations been consulted? 
All Member States roadworthiness testing authorities, the 
coordinating body of roadworthiness testes (CITA), DEKRA, the garage 
equipment association and private testing organisations have been 
consulted. 

ISSN 0254-1475 
COM(91) 244 final 
DOCUMENTS 
EN 07 
Catalogue number : CB-CO-91-286-EN-C 
ISBN 92-77-73783-2 
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