Today, polydicyclopentadiene (PDCPD) is a promising polymeric material for automotive components. It is a liquid moulding resin that is processed via a reaction injection moulding system. PDCPD is used to make a kit of parts for KAMAZ vehicle "lower belt", bumper face guards, air intakes. It was found during the operation that the KAMAZ side step frame made of PDCPD failed. The comprehensive investigation revealed that the causes of the part failure were environmental factors, thermal degradation, quality of the raw materials, as well as failure to comply with the production process. The study of the IR spectra of PDCPD samples showed that the failed part (unlike the standard samples) featured a more intensive peak at around 1745 cm-1, which corresponded to the vibrations of carbonyl groups –С=О, which was indicative of the formation of the oxidized structures. The probability of formation of these structures can be a result of the thermal oxidation of the end product due to violation of the production process, operation at increased temperatures, and UV exposure, as well as low-quality raw materials.