The results of engine bench tests of a 2.0l common-rail high-pressure injection passenger car diesel engine fuelled by B70 biodiesel blend are compared with the corresponding results of baseline tests with standard EN 590 diesel fuel. Engine performance and carbon monoxide (CO), total hydrocarbon (THC), and nitrogen oxide (NO x) emissions were measured. Also, indicative particulate sampling was made with a simplified undiluted exhaust sampler. The aim of this study was to understand better how the engine's electronic control unit (ECU) responds to the different fuel qualities. A series of characteristic operation points for engine testing is selected to serve this purpose better. Data acquisition of the engine ECU variables was made through INCA software. Also, additional data acquisition based on external sensors was carried out by means of Labview software. The results enhance understanding of the engine ECU behaviour with the B70 biodiesel blend. Also, they are compared with what is known from the related literature for the behaviour of common-rail diesel engines with biodiesel blends.