Variable Valve Timing (VVT) is an advanced technology implemented in internal combustion engines to optimize the opening and closing timing of the intake and exhaust valves. Its primary objective is to improve engine performance, fuel efficiency, and reduce emissions by dynamically adjusting the valve timing based on the engine's operating conditions i.e. engine speed and load conditions. However, the VVT system may experience various operational issues caused due to low engine oil levels, contaminated engine oil, solenoid malfunctions, and camshaft phaser issues, which can adversely affect engine performance, fuel efficiency, and emissions. This paper provides an in-depth analysis of VVT malfunctions, specifically attributed to the resonance effect of VVT components at various engine RPMs & oil temperature. The study also explains the phenomenon causing VVT sluggishness during advance phase due to resonance between oil pulsation & VVT components. Other factors contributing to VVT malfunctions, including variations in solenoid current, solenoid movement, oil pressure fluctuations, VVT sprocket and camshaft movement were also taken into consideration while investigating. This study concluded that VVT malfunctioning is primarily due to resonance between oil pulsation and VVT components at a particular engine speed and oil temperature. This study offers important information related to VVT sluggishness behavior analysis that can be used as a reference while troubleshooting VVT malfunction. ABBREVIATIONS VVT : Variable valve timing