United Nations Environment Programme

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Tool 7: Maintenance

A malfunctioning engine will emit substantially more pollutants and consume more fuel than one that is well-tuned. Typically, only 10-15% of the vehicles in an ordinary fleet produce about 50% of emissions. Proper inspection and maintenance programmes ensure that these vehicles are identified and repaired. Good maintenance will also extend the life of all parts of the vehicle, provide environmental benefits, and improve overall traffic safety.


 Photo: Fleet Forum

Keep your engine in good condition: Regular inspections and maintenance procedures are essential for keeping your fleet operating with minimal environmental consequences. Well-performed inspections and follow-up repairs typically improve fuel consumption by 3-7% and reduce emissions of particulate matter, NOx and VOC by 10-20% (these reductions depend on the initial condition of the fleet).


The Action-drivers Sheet in the Inventory and Options (Tool 18) indicates expected savings in fuel that are attainable through better inspection and maintenance procedures.

In its initial stages, an inspection and maintenance programme does not need to be highly advanced. Fuel economy improvements and environmental benefits can be obtained through simple tasks such as checking that the engine is properly tuned, that filters and fuel injectors are clean, and that the tires are properly inflated and aligned. Many inspection and maintenance programmes also typically include other steps such as safety checks of brakes and suspension.

In later phases, more comprehensive steps can be taken, such as exhaust measurement of smoke opacity (which can help in the identification of malfunctioning engines). Adding environmental components to your maintenance programme requires some knowledge, but is usually not costly (See the example of the Jakarta bus fleet).




Mechanic conducting a "tune-up" for WFP/IFRC. Photo: Fleetforum


It is crucial to keep the engine operating in the conditions intended by the manufacturer.

When performing a full engine tune-up, mechanics usually ensure that:

  • The fuel injection system and the distributor system are working well;
  • The fuel and the air filters are clean; and
  • The spark plugs are not fouled.

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