Abstract. This paper presents the analysis of costs and cost-efficiency of the repair of modern fuel injection systems in compression-ignition engines. The requirements for modern Diesel engines are low emission of toxic substances into the atmosphere and low fuel consumption. In order to meet the rigorous standards, the Common Rail fuel injection system has been implemented. By increasing fuel injection pressure to 200 MPa and introducing multi-stage dosing, engine designers have improved the process of air-fuel mixture combustion and engine ecological and economic parameters. The price for these changes is an accelerated wear of fuel injection equipment in modern CI engines. Regular fuel filter replacement and periodical cleaning of the systems would minimise the risk of damage. Unfortunately, most users do not comply with vehicle servicing times, and come to car repair shops only when a failure occurs, but then it is too late and the repair costs are high.
Key words: Common Rail system, injection pump, fuel injector, high pressure system, low pressure system, Diesel engine.