Automobiles are subjected to varied harmonic vibration loads that are generated by the engine at various RPM levels within the operating condition. Facing resonant frequencies of PCB within the operating frequency range can cause damage to PCB due to large amplitudes generated. To avoid the resonance situation, either external excitation frequency should be changed or natural frequency of the component. Normally, we do not have any control over external excitation frequency and hence the practical approach is to alter/change the natural frequency. Natural frequency according to the formula depends on the mass (inversely proportional) and stiffness (directly proportional). In practical situations, the natural frequency is altered by changing the stiffness rather than mass. This can be done by changing the boundary conditions (support), the addition of ribs/stiffeners, change in thickness of stiffeners, or by using stiffer material, etc. More accurate results can be observed by achieving convergence in meshing and accurate modelling of PCB. This paper demonstrates free flexural vibrations analysis of a stiffened PCB investigated by using finite element analysis (FEA). The PCB considered for analysis is inside the engine electronic control unit (ECU) of an automobile which is mounted near the engine. The reason to consider this PCB is that maximum vibrations are encountered here.